Ultrasonic medical device and associated method

ABSTRACT

A medical system includes a carrier and a multiplicity of electromechanical transducers mounted to the carrier, the transducers being disposable in effective pressure-wave-transmitting contact with a patient. Energization componentry is operatively connected to a first plurality of the transducers for supplying the same with electrical signals of at least one pre-established ultrasonic frequency to produce first pressure waves in the patient. A control unit is operatively connected to the energization componentry and includes an electronic analyzer operatively connected to a second plurality of the transducers for performing electronic 3D volumetric data acquisition and imaging (which includes determining three-dimensional shapes) of internal tissue structures of the patient by analyzing signals generated by the second plurality of the transducers in response to second pressure waves produced at the internal tissue structures in response to the first pressure waves. The control unit includes phased-array signal processing circuitry for effectuating an electronic scanning of the internal tissue structures which facilitates one-dimensional (vector), 2D (planar), and 3D (volume) data acquisition. The control unit further includes circuitry for defining multiple data gathering apertures and for coherently combining structural data from the respective apertures to increase spatial resolution. When the data gathering apertures are contained in a flexible web or carrier so that the instantaneous positions of the data gathering apertures are unknown, a self-cohering algorithm is used to determine their positions so that coherent aperture combining can be performed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.09/153,451 filed Sep. 15, 1998, now U.S. Pat. No. 6,306,090. ApplicationSer. No. 09/153,451 was filed as a continuation of application Ser. No.08/839,971 filed Apr. 24, 1997, now U.S. Pat. No. 5,871,446, which wasfiled as a continuation in part and a division of application Ser. No.08/510,104 filed Aug. 1, 1995 now U.S. Pat. No. 5,666,953. ApplicationSer. No. 08/510,104 was in turn filed as a division of application Ser.No. 07/819,120 filed Jan. 10, 1992, now U.S. Pat. No. 5,437,278. Thisapplication is also a continuation of application Ser. No. 08/892,955filed Jul, 16, 1997 now U.S. Pat. No. 6,023,632.

BACKGROUND OF THE INVENTION

This invention relates to a device or system for use in medicaldiagnoses and treatment. The device or system is especially useful formedical imaging purposes to enable a visual inspection of internaltissue structures.

In recent years, the escalation of medical costs has capturedsubstantial media and regulatory attention. One reason for theescalating costs is the ever increasing use of expensive machines andtesting techniques. Computed assisted tomography (CAT scanning),magnetic resonance imaging (MRI) and some radiological techniques havebeen in the forefront of contributing to mounting medical costs. Inaddition to being expensive, these devices are heavy and bulky, makingthem ill suited to transport.

In this age of rapidly escalating medical costs, minimally invasiveoperations have become the method of choice for diagnosis and treatment.In many cases, endoscopic, laparoscopic and radiographic techniques havesuperseded older diagnostic and therapeutic surgical techniques.

Ultrasonic imaging tools are not uncommon in medical offices. Theseexisting devices invariably include a probe provided at a distal or freeend with an ultrasonic transducer. The operator moves the probe over askin surface of a patient while viewing images generated on a videomonitor. Upon detecting an image containing information of interest, theoperator presses a button to record the image.

The images produced during a conventional ultrasonic scanning procedureare not easily decipherable. Even physicians intimately familiar withinternal tissue structures of human beings find it difficult to readconventional ultrasonically generated images without substantialtraining.

Conventional ultrasound images are two-dimensional (2D) and represent across-sectional cut or plane through internal tissues. The data neededfor these 2D images are acquired electronically using the probe. Theprobe scans electronically in a single lateral or length dimension toscan a beam and hence is referred to as a one-dimensional (1D)transducer array; and the second dimension in a 2D image is the range ordepth dimension (i.e. into the body). Interest in three-dimensional (3D)ultrasound imaging is increasing rapidly, notwithstanding the fact thatpresently, it is not possible to obtain electronic 3D volumetric dataacquisition. Electronic 3D volumetric data acquisition requires a probethat can electronically scan in a width dimension as well as a lengthdimension (i.e. the probe must incorporate a 2D transducer array). Suchprobes are not currently available, and are not expected to be in thenear future due to multiplicative complexities known to those skilled inthe art in implementing a 2D transducer array, However, 1.5D transducerarrays are available. These arrays scan only in one dimension (i.e. thelength dimension) as the 1D transducer arrays; however, they include afew additional rows of transducer elements in the width dimension givingthe appearance of a rectangular 2D array. The purpose of the fewadditional rows (where each row is effectively a 1D array consistingtypically of approximately 100 transducer elements) of elements is toprovide better focus in the width dimension as a function of depth.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an imaging device orsystem which is relatively inexpensive and easy to transport.

It is another object of the present invention to provide an alternativeto conventional medical imaging systems.

A further object of the present invention is to provide a medicalimaging system which exhibits reduced costs over conventional imagingsystems such as CAT scanners and MRI machines.

A particular object of the present invention is to provide a medicalimaging system which can be used during the performance of so-calledminimally invasive medical operations.

It is an additional object of the present invention to provide a medicalimaging system which is portable.

Another object of the present invention is to provide a medicaloperating method which provides real time imaging in a cost effectivemanner.

A particular object of the present invention is to provide electronic,three-dimensional (3D) volumetric data acquisition using an ultrasonicimaging device or system. Another object of the present invention is toprovide both conventional two-dimensional (2D) image and 3D imageprocessing.

These and other objects of the present invention will be apparent fromthe drawings and descriptions herein.

SUMMARY OF THE INVENTION

A medical system comprises, in accordance with the present invention, acarrier and a multiplicity of electromechanical transducers mounted tothe carrier, the transducers being disposable in effectivepressure-wave-transmitting contact with a patient. Energizationcomponentry is operatively connected to a first plurality of thetransducers for supplying the same with electrical signals of at leastone pre-established ultrasonic frequency to produce first pressure wavesin the patient. A control unit is operatively connected to theenergization componentry and includes an electronic analyzer operativelyconnected to a second plurality of the transducers for performingelectronic 3D volumetric data acquisition and imaging (which includesdetermining three-dimensional shapes) of internal tissue structures ofthe patient by analyzing signals generated by the second plurality ofthe transducers in response to second pressure waves produced at theinternal tissue structures in response to the first pressure waves. Thecontrol unit includes phased-array signal processing circuitry foreffectuating an electronic scanning of the internal tissue structureswhich facilitates one-dimensional (vector), 2D (planar) and 3D (volume)data acquisition. Vector data acquisition is a special case of planardata acquisition, which is a special case of volume data acquisition.

In a specific embodiment of the invention, the carrier is rigid. Morespecifically, the carrier comprises a plurality of rigid modularsubstrates rigidly connected to one another, each of the substratesholding a plurality of the transducers. The modular substrates areoff-the-shelf components such as the 1.5D (or 1.75D) transducer arraysfound in conventional, premium probes, with on the order of 100piezoelectric transducers (or elements) disposed in a tightly packedline along a length dimension of the substrate. Inter-element spacing istypically one wavelength or less to support full scanning along thelength dimension. A width dimension of a modular substrate carriessubstantially fewer (e.g. less than 10) piezoelectric transducers. Boththe inter-element spacing and element size along the width dimension istypically a few or several wavelengths. The electronic scanning ofinternal tissue structures of a patient along the length dimension isperformed conventionally by the control unit. The control unit alsoprovides electronic scanning of internal tissue structures of a patientin the width dimensions of the modular substrates, where the density ofthe transducers is low, using a procedure unique to the presentinvention which is described in detail below. The rigid carrier may beplanar (flat) or curved in its shape so as to be conformal to apatient's body.

The carrier may be provided with a fluid-filled flexible bag disposablein contact with the patient for facilitating transmission of the firstpressure waves into the patient from the first plurality of transducersand reception of the second pressure waves by the second plurality oftransducers.

In accordance with a feature of the present invention, the phased-arraysignal processing circuitry includes switching circuitry or other meansoperatively connected to the energization componentry for independentlyvarying the time-delays or phases of the electrical signals across thefirst plurality of the transducers to effectuate an electronic scanningof the internal tissue structures of the patient by the first pressurewaves. Alternatively or additionally, the phased-array signal processingcircuitry includes switching circuitry or other means for varyingsampling times or phases of the second pressure waves received at thesecond plurality of the transducers and further includes combiningcircuitry for combining the sampled signals to effectuate an electronicscanning of the second pressure waves by the second plurality oftransducers. The effect of the aforementioned phased-array signalprocessing circuitry is to dynamically focus the pressure waves intospatially directed beams of energy and to provide electronic sequentialbeam scanning and/or beam steering in order to interrogate the internaltissue structures of the patient. The principles of sequential beamscanning and beam steering are known to those skilled in the art.

The transmitting transducers may be used also for receiving. However,there may be transducers which are dedicated to one task or the other.

In accordance with another feature of the present invention, the controlunit includes circuitry operatively connected to the energizationcomponentry for varying the frequency to facilitate collection ofthree-dimensional structural data pertaining to tissue structures atdifferent depths in the patient.

A system in accordance with the present invention is generally useful inthe generation of 2D and 3D images of internal tissue structures of aliving being such as a human medical patient. To that end, at least onedisplay is operatively connected to the electronic analyzer forproviding an image of the internal tissue structures of the patient.

A related medical method comprises, in accordance with the presentinvention, (a) placing a carrier holding a multiplicity ofelectromechanical transducers and a patient adjacent to one another sothat the transducers are disposed in effectivepressure-wave-transmitting contact with the patient, (b) supplying afirst plurality of the transducers with electrical signals of at leastone pre-established ultrasonic frequency to produce first pressure wavesin the patient, (c) receiving, via a second plurality of thetransducers, second pressure waves produced at internal tissuestructures of the patient in response to the first pressure waves, and(d) performing electronic 3D volumetric data acquisition by solely anelectronic scanning of said internal tissue structures and performingelectronic 3D imaging (which includes determining three-dimensionalshapes) of the internal tissue structures in part by analyzing signalsgenerated by the second plurality of the transducers in response to thesecond pressure waves. At least one of the supplying and receiving stepsis executed to effectuate electronic scanning of the internal tissuestructures.

The electronic scanning may be accomplished by varying the time delaysor phases of the electrical signals across the first plurality of thetransducers to effectuate a phased-array electronic scanning of internaltissues of the patient by the first pressure waves. Alternatively oradditionally, the electronic scanning is accomplished by varyingsampling times or phases of the second plurality of the transducers toeffectuate an electronic scanning of the second pressure waves by thesecond plurality of transducers. In the former case, the varying of thetime delay or phase of the electrical signals may include operatingswitching circuitry operatively connected to the first plurality of thetransducers. In the latter case, the varying of the time delay or phaseof the electrical signals may include operating switching circuitryoperatively connected to the second plurality of the transducers.

The method preferably further comprises disposing a flexiblefluid-filled bag between the patient and the carrier and transmittingthe first pressure waves and receiving the second pressure waves throughthe fluid filled flexible bag. The flexible bag ensures positivepressure wave transmission and reception and effectively conforms theultrasonic system to the irregular body profile of the patient.

A medical system comprises, in accordance with another conceptualizationof the present invention, a carrier, a multiplicity of electromechanicaltransducers mounted to the carrier, and energization componentryoperatively connected to a first plurality of the transducers forsupplying the same with electrical signals of at least onepre-established ultrasonic frequency to produce first pressure waves inthe patient. The system further comprises a control unit operativelyconnected to the energization componentry for operating the same toproduce the first pressure waves in the patient. The control unitincludes an electronic analyzer operatively connected to a secondplurality of the transducers for performing electronic 3D volumetricdata acquisition and imaging of internal tissues of the patient byanalyzing signals generated by the second plurality of the transducersin response to second pressure waves produced at internal tissues of thepatient in response to the first pressure waves. The control unit isoperatively connected to the second plurality of the transducers togather and organize data from the second plurality of the transducers sothat the second plurality of transducers define a plurality of datagathering apertures which are unique to this invention. A subset of thesecond plurality of the transducers is used in each data gatheringaperture. Data can be gathered from the defined data gathering aperturessequentially in time or simultaneously. Electronic scanning is performedby each data gathering aperture to interrogate and acquire structuraldata from a desired spatial region. The control unit includes coherentaperture combining (CAC) circuitry for coherently combining structuraldata from the respective data gathering apertures, which is a uniquefeature of this invention. The resultant effective increase in totalaperture size improves the resolution capability of the imaging system.The control unit may also include circuitry for noncoherently combiningstructural data, which allows extended images to be created withoutincreasing the imaging resolution.

In a particular embodiment of the present invention, the transducers aredisposed on or form rigid substrates in turn movably connected to oneanother, e.g., via a flexible web carrier. In this embodiment, theindividual substrates form separate data gathering apertures, and thecoherent aperture combining circuitry includes or is connected toposition determination elements for determining relative positions andorientations of the substrates relative to one another. The positiondetermination elements may include a multiplicity of point scatterers, asubset of which are visible to (i.e., can be scanned by) each of thesubstrates in question, the position determination element furtherincluding programmed componentry operatively connected to theenergization componentry for periodically scanning the point scattererswith first ultrasonic pressure waves and calculating instantaneouspositions of the point scatterers as seen by each substrate in questionusing the reflected second ultrasonic pressure waves. Alternatively, thefirst ultrasonic pressure wave signals received directly by a pluralityof distinct transducers (different from those used to generate the firstpressure waves) can be used in place of point scatterers (and theirassociated reflected second pressure waves) to calculate theinstantaneous positions of the distinct transducers as seen by each ofthe substrates in question. In either case, the position determinationelements include circuitry for executing computations according to aself-cohering algorithm that computes each substrate's relative positionand orientation using the instantaneous position measurements, andadjusts the signals from the coherently combined apertures so they canbe added together constructively.

For medical diagnostic and treatment purposes, at least one display isoperatively connected to the electronic analyzer for providing an imageof the internal tissue structures of the patient.

An associated medical method comprises, in accordance with the presentinvention, (i) providing a carrier holding a multiplicity ofelectromechanical transducers forming a plurality of data gatheringapertures, (ii) placing the carrier and a patient adjacent to oneanother so that the transducers are disposed in effectivepressure-wave-transmitting contact with the patient, (iii) supplying afirst plurality of the transducers with electrical signals of at leastone pre-established ultrasonic frequency to produce first pressure wavesin the patient, (iv) receiving, via a second plurality of thetransducers, second pressure waves produced at internal tissuestructures of the patient in response to the first pressure waves, and(v) performing electronic 3D volumetric data acquisition and imaging(which includes determining three-dimensional shapes) of the internaltissue structures by analyzing signals generated by the second pluralityof the transducers in response to the second pressure waves.

The carrier may take any of several forms. In one form, the carrier is aflexible web, with the transducers being individual scalar elementsdistributed in an array throughout at least a substantial portion of theweb. In this case, the various data gathering apertures are defined bysignal processing: either the first plurality of transducers isenergized in groups, or the second plurality of transducers is sampled(i.e. received) in groups, or both. This electronic grouping oftransducers may be varied from instant to instant, depending on theimaging requirements. In another form of the carrier, a plurality ofrigid carrier substrates are movably attached to one another (e.g., viaa flexible web or sheet), each substrate bearing a respective set ofscalar transducer elements. The substrates with their respectivetransducers easily or conveniently (but not necessarily) definerespective data gathering apertures. In either of these forms of thecarrier, one or both of the steps of transmitting and receiving mayinclude coherently combining structural data from the respectiveapertures using CAC. In both cases, a self-cohering algorithm is used tocompute relative positions and orientations of the transducer scalarelements or rigid carrier substrates, as the case may be, usinginstantaneous position measurements and to adjust signals from eachcoherently combined aperture to enable constructive addition of thosesignals from the coherently combined apertures.

The carrier may alternatively take the form of a singular rigidstructure constructed using scalar transducer elements arranged in thelikeness of an array, or a rigid form constructed from a plurality ofmodular rigid substrates (where each substrate consists of one or more1D or 1.5D arrays, and where each array contains a plurality of scalartransducer elements) rigidly connected to one another and arranged inthe likeness of an array. In these cases, the positions and orientationsof all transducers relative to each other are known; no calibration orposition determination circuitry is necessary. Signal transmissionapertures and data gathering apertures are formed and used toelectronically scan desired regions and electronically acquire 3Dvolumetric data. Each signal transmission aperture is formed by groupinga first plurality of transducer elements and each data gatheringaperture is formed by grouping a second plurality of transducerelements. Coherent aperture combining can be used to combine thestructural data from multiple data gathering apertures without aself-cohering algorithm. Noncoherent combination of structural data fromrespective apertures may also be performed.

Where CAC is employed to combine structural data from multiple datagathering apertures and the relative positions and orientations of thoseapertures are unknown, the coherent combining of structural datapreferentially includes determining relative positions and orientationsof the data gathering apertures relative to one another. Where pointscatterers are visible to transducers on the data gathering apertures,the determining of relative positions and orientations of theseapertures includes periodically scanning, using a plurality oftransducer elements on the respective apertures, of the point scattererswith first ultrasonic pressure waves and calculating the instantaneouspositions of the point scatterers as seen by the respective plurality oftransducer elements using reflected pressure waves. Where a distinctplurality of transducers are used in place of point scatterers, directmeasurements of pressure waves received by those distinct transducersare used to calculate the instantaneous positions of those distincttransducers relative to respective plurality of transducers transmittingthe first pressure waves. In either case, the determining of relativepositions and orientations of the data gathering apertures entailsexecuting computations according to a self-cohering algorithm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a medical diagnostic system, which mayutilize or incorporate an ultrasonographic imaging device in accordancewith the present invention.

FIG. 2 is a flow-chart diagram illustrating steps in a mode of operationof the diagnostic system of FIG. 1.

FIG. 3 is a flow-chart diagram illustrating steps in another mode ofoperation of the diagnostic system of FIG. 1.

FIG. 4 a block diagram of a further medical diagnostic system.

FIG. 5 is a diagram showing the composition of a data string or moduleused in the system of FIG. 4.

FIG. 6 is a block diagram of a computerized slide scanning system.

FIG. 7 is a block diagram of a device for measuring a diagnosticparameter and transmitting the measurement over the telephone lines.

FIG. 8 is a diagram of an ultrasonography device.

FIG. 9 is a diagram showing a modification of the device of FIG. 8.

FIG. 10 is a block diagram of an ultrasonographic imaging apparatussimilar to the device of FIGS. 8 and 9, for use in diagnostic andtherapeutic procedures.

FIG. 11 is a block diagram showing a modification of the apparatusillustrated in FIG. 10.

FIG. 12 is partially a schematic perspective view and partially a blockdiagram showing use of an ultrasonographic imaging device in a minimallyinvasive diagnostic or therapeutic procedure.

FIG. 13 is a partial schematic perspective view including a blockdiagram showing use of an ultrasonographic imaging device in anotherminimally invasive diagnostic or therapeutic procedure.

FIG. 14 is a schematic perspective view of yet another ultrasonographicimaging device which includes a sensor vest in a closed, useconfiguration.

FIG. 15 is a schematic perspective view of the sensor vest of FIG. 14,showing the vest in an open configuration.

FIG. 16 is partially a schematic perspective view and partially a blockdiagram of an ultrasonic diagnostic imaging device.

FIG. 17 is partially a schematic perspective view and partially a blockdiagram of the ultrasonic diagnostic imaging device of FIG. 16, showingthe device in use with a patient.

FIG. 18 is partially a schematic perspective view and partially a blockdiagram of another ultrasonic diagnostic imaging device, showing thedevice in use with a patient.

FIG. 19 is partially a schematic perspective view and partially a blockdiagram of the ultrasonic diagnostic imaging device of FIGS. 17 and 18,showing a modification of the device of those figures.

FIG. 20 is partially a schematic exploded perspective view and partiallya block diagram of an ultrasonographic device or system related to thepresent invention.

FIG. 21 is a schematic perspective view showing use of the system ofFIG. 20 in performing a laparoscopic operation.

FIGS. 22A and 22B are schematic perspective views showing use of anotherultrasonographic device related to the present invention.

FIG. 23A is a schematic perspective view of a further ultrasonographicdevice related to the present invention.

FIG. 23B is a schematic perspective view showing use of theultrasonographic device of FIG. 23A.

FIG. 24 is a schematic perspective view of an ultrasonographic device.

FIG. 25 is a schematic perspective view of another ultrasonographicdevice.

FIG. 26 is a schematic perspective view of the ultrasonographic deviceof FIG. 25, showing the device in use on a patient.

FIG. 27A is a schematic front elevational view of a video screen displayconfiguration utilizable in the ultrasonographic device of FIGS. 25 and26.

FIG. 27B is a schematic front elevational view of a further video screendisplay configuration utilizable in the ultrasonographic device of FIGS.25 and 26.

FIG. 28 is a schematic partial perspective view of a modification of theultrasonographic device of FIGS. 25 and 26, showing a mode of use of thedevice in a surgical treatment or a diagnostic procedure.

FIG. 29 is partially a schematic perspective view and partially a blockdiagram of an ultrasonic imaging system in accordance with the presentinvention.

FIG. 30 is a schematic perspective view, on a larger scale, of a modulartransducer package or array aperture included in the system of FIG. 29.

FIG. 31 is a diagram of two relative spaced and rotated modulartransducer packages or array apertures similar to that of FIG. 30,showing geometric parameters in a calculation of relative position andorientation.

FIG. 32 is partially a schematic perspective view and partially a blockdiagram showing a modification of the ultrasonic imaging system of FIG.29.

FIG. 33 is a block diagram of components of a phased-array signalprocessing circuit shown in FIG. 32, also showing components from FIG.29.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed chiefly to an imaging device andparticularly to an ultrasonographic imaging device utilizable indiagnostic and therapeutic procedures. The ultrasonographic imagingdevice of the present invention is described generally hereinafter withreference to FIG. 8 et seq. The ultrasonographic imaging device, andparticularly image derivation or construction portions thereof, can beemployed as an image generating apparatus or scanner 42 in the medicaldiagnostic system of FIG. 1 or a diagnostic image generating apparatus78 a, 78 b, 78 i in the medical diagnostic system of FIG. 4.Alternatively or additionally, the ultrasonographic imaging device canbe employed in carrying out certain minimally invasive diagnostic ortherapeutic operations, examples of which are illustrated schematicallyin FIGS. 12 and 13.

As illustrated in FIG. 1, a medical diagnostic system comprises a device20 for monitoring and measuring a biological or physiological parameter.Monitoring and measuring device 20 is juxtaposable to a patient forcollecting individualized medical data about the patient's condition.Device 20 may take the form of an electronic thermometer, an electronicblood pressure gauge, a pulmonary function apparatus, a Doppler studyapparatus, an EEG machine, an EKG machine, an EMG machine, or a pressuremeasurement device, etc., or include a plurality of such components.

Monitoring and measuring device 20 is connected at an output to adigitizer 22 which converts normally analog type signals into codedbinary pulses and transmits the resulting digital measurement signal toa computer 24. Digitizer 22 may be incorporated into a housing (notshown) enclosing all or part of the monitoring and measuring device 20.Moreover, digitizer may be an integral part of monitoring and measuringdevice 20.

Computer 24 receives instructions and additional input from a keyboard26. Keyboard 26 is used to feed computer 24 information for identifyingthe patient, for example, the patient's age, sex, weight, and knownmedical history and conditions. Such medical conditions may include pastdiseases and genetic predispositions.

Computer 24 is also connected to an external memory 28 and an outputdevice 30 such as a printer or monitor. Memory 28 stores medical datafor a multiplicity of previously diagnosed medical conditions which aredetectable by analysis of data provided by monitoring and measuringdevice 20.

As illustrated in FIG. 2, monitoring and measuring device 20 detects amagnitude of a predetermined biological or physiological parameter in astep 32. Digitizer 22 converts the detected magnitude into apre-established digital format in a step 34 and transmits the digitalsignal to computer 24 in a step 36. Computer 24 is operated in a step 38to compare the digitized data from monitoring and measuring device 20with the data stored in memory 28 and to derive a diagnosis as to thepatient's condition. The diagnosis is then communicated to the user(operator) and to the patient via output device 30 in a step 40.

If monitoring and measuring device 20 measures a physiological functioncharacterized by a plurality of different variables, for example, theelectric potential at different points on the patient's body (EEG, EKG,EMG), these variables may be broken down by computer 24 into one or moreparameters, e.g., a frequency packet. The measured values of thepre-established parameters are then compared with parameter rangesstored in memory 28 for the type of parameter and the kind of patient,as characterized by sex, age, weight, etc. If the measured values of thepre-established parameters fall within expected ranges, as stored inmemory 28, then computer 28 communicates a “normalcy” finding viaprinter 30. If, on the contrary, the measured values of one or moreparameters fall outside the normal ranges, then a diagnosis of apossible medical condition is printed out.

As further illustrated in FIG. 1, the medical diagnostic system maycomprise, in addition to or alternatively to monitoring and measuringdevice 20, image generating apparatus or scanner 42 for generating inelectrically encoded form a visually readable image of an organic partof the patient. Scanner 42 may take the form of an MRI apparatus, a CATscanner, an X-ray machine, an ultrasonography apparatus (see FIGS. 8-15and 20), or a video camera with or without magnification optics formagnifying a sample on a slide. The video camera can be used forobtaining an image of a portion of a patient's skin.

Scanner 42 is connected via an interface 44 to computer 24.

As shown in FIG. 3, scanner 42 obtains an image of a tissue or organ ina step 46. The image is digitized, either by scanner 42 or interface 44in a step 48, and is transmitted to computer 24 in a step 50. Computer24 is operated in a step 52 to analyze the image from scanner 42 anddetermine specific values for a multiplicity of predeterminedparameters. For example, in the event that scanner 42 takes theparticular form of a video camera for dermatological diagnosis, an imageof a skin surface of a patient is analyzed by computer 24 to derive suchparameters as percentage of skin covered by abnormal condition, therange of sizes of individual ulcers, the range of color variation (e.g.,whether bleeding is symptomatic).

The specific values of pre-established parameters calculated by computer24 from electrically encoded images transmitted from scanner 42 arecompared by computer 24 with previously determined parameter rangesstored in memory 28. For example, if a pregnant woman's fetus is beingscanned by ultrasonography, the lengths of the fetal appendages, arms,legs, fingers, etc., are compared with each other and with respectivefetal appendage ranges recorded in memory 28 for the stage of pregnancy,weight of the fetus, and possibly weight of the mother. In the eventthat any appendages are missing or are of abnormal length, a diagnosisas to possible deformity is printed out. Organs internal to the fetusmay be similarly examined automatically by scanner 42 and computer 24.In more advanced stages of pregnancy, physiological functions such asthe heart rate of the fetus may be automatically monitored for abnormalconditions.

The analysis performed by computer 24 on the image from scanner 42 willdepend in part on the region of the patient's body being scanned. If awoman's breast or a person's cortex is being monitored for tumorousgrowths, computer 24 is programmed to separate the tissue image intoregions of different textures. The different textured regions areparameterized as to size, shape and location and the derived parametersare compared to values in memory 30 to determine the presence of atumor. Additional analysis is undertaken to detect lines in an imagewhich may indicate the presence of an organic body.

A similar analysis is undertaken to evaluate a tissue specimen on aslide. The texture and line scanning may be repeated at differentmagnification levels if, for example, the tissue sample is a slice of anorgan wall. On a high magnification level, the texture and line analysiscan serve to detect microorganisms in blood.

Memory 28 may store entire images related to different diseases. Forexample, memory may store images of skin conditions in the event thatscanner 42 takes the form of a video camera at a dermatologicaldiagnosis and treatment facility. In a step 54 (FIG. 3), computer 24compares the image of a patient's skin with previously stored images inmemory 28, for example, by breaking down the current image into sectionsand overlaying the sections with sections of the stored images, atvariable magnification levels.

In the event that scanner 42 takes the form of an MRI apparatus, a CATscanner or an ultrasonographic scanner such as those describedhereinafter with references to FIGS. 8-15 and 20, the images stored inmemory 28 are of internal organic structures. In step 54 (FIG. 3),computer 24 compares images of a person's internal organs withpreviously stored organ images in memory 28. Computer 24 partitions theimage from the MRI apparatus or CAT scanner into subareas and overlaysthe subareas with sections of the stored images, at variablemagnification levels.

In a final step 40 (FIG. 3), computer 24 communicates the results of itsdiagnostic evaluation to a user or patient.

As illustrated in FIG. 4, a medical diagnostic system comprises aplurality of remote automated diagnostic stations 60 a and 60 bconnected via respective telecommunications inks 62 a and 62 b to acentral computer 64. Each diagnostic station 60 a, 60 b may take theform shown in FIG. 1, local computer 24 communicating via link 62 a, 62b with central computer 64. Alternatively, each diagnostic station 60 a,60 b may take the form shown in FIG. 4 and include a respectiveplurality of monitoring and measuring devices 66 a, 66 b, . . . 66 noperatively connected to a local computer 68 via respective digitizeroutput units 70 a, 70 b, . . . 70 n. Computer 68 is fed instructions anddata from a keyboard 72 and communicates diagnostic results via amonitor 74 or printer 76. As discussed hereinabove with reference tomonitoring and measuring device 20 of FIG. 1, each monitoring andmeasuring device 66 a, 66 b, . . . 66 n is juxtaposable to a patient forcollecting individualized medical data about the patient's condition.Monitoring and measuring devices 66 a, 66 b, . . . 66 n may respectivelytake the form of an electronic thermometer, an electronic blood pressuregauge, a pulmonary function apparatus, a Doppler study apparatus, an EEGmachine, an EKG machine, an EMG machine, or a pressure measurementdevice, etc.

Digitizers 70 a, 70 b, . . . 70 n convert normally analog type signalsinto coded binary pulses and transmit the resulting digital measurementsignals to computer 68. Digitizers 70 a, 70 b, . . . 70 n may beincorporated into the housings or casing (not shown) enclosing all orpart of the respective monitoring and measuring devices 66 a, 66 b, . .. 66 n.

Keyboard 72 is used to feed computer 68 information for identifying thepatient, for example, the patient's age, sex, weight, and known medicalhistory and conditions. Such medical conditions may include pastdiseases and genetic predispositions.

As further illustrated in FIG. 4, a plurality of diagnostic imagegenerating apparatuses or scanners 78 a, 78 b, . . . 78 i are alsoconnected to central computer 64 via respective hard-wired or wirelesstelecommunications links 80 a, 80 b, . . . 80 i. Scanners 78 a, 78 b, .. . 78 i each generate in electrically encoded form a visually readableimage of an organic part of the patient. Scanners 78 a, 78 b, . . . 78 imay each take the form of an MRI apparatus, a CAT scanner, an X-raymachine, an ultrasonography apparatus (FIGS. 8-15 and 20), or a videocamera with or without magnification optics for magnifying a sample on aslide.

Because of the enormous quantity of data necessary for storing images,central computer 64 is connected to a bank of memories 82 at a centralstorage and information processing facility 84. Diagnosis of patientconditions may be undertaken by central computer 64 alone or incooperation with local computers 24 or 68.

As illustrated in FIG. 5, local computers 24 and 68 transmit informationto central computer 64 in data packets or modules each include a firststring of binary bits 86 representing the transmitting station 60 a, 60b, a second bit string 88 identifying the patient, a bit group 90designating the parameter which is being transmitted, another bit group92 coding the particular measured value of the parameter, a set of bits94 identifying the point on the patient at which the measurement wastaken, and another bit set 96 carrying the time and date of themeasurement. Other bit codes may be added as needed.

As shown in FIG. 6, a computerized slide scanning system comprises aslide carrier 100 mountable to a microscope stage and a slidepositioning device 102 mechanically linked to the slide carrier 100 forshifting the carrier along a path determined by a computer 104. Computer104 may be connected to an optional transport or feed assembly 106 whichdelivers a series of slides (not shown) successively to slide carrier100 and removes the slides after scanning.

Computer 104 is also connected to an optical system 108 for modifyingthe magnification power thereof between successive slide scanningphases. Light emerging from optical system 108 is focused thereby onto acharge coupled device (“CCD”) 110 connected to computer 104 for feedingdigitized video images thereto.

Computer 104 performs a line and texture analysis on the digitized imageinformation from CCD 110 to determine the presence of different organicstructures and microorganisms. The different textured regions areparameterized as to size, shape and location and the derived parametersare compared to values in a memory to identify microscopic structures.The texture and line scanning is repeated at different magnificationlevels.

Computer 104 may be connected to a keyboard 112, a printer 114, and amodem 16. Modem 116 forms part of a telecommunications link forconnecting computer 104 to a remote data processing unit such ascomputer 64 in FIG. 4.

Image generating apparatus 42 in FIG. 1 may take the form of thecomputerized slide scanning system of FIG. 6.

As shown in FIG. 7, a device for measuring a diagnostic parameter andtransmitting the measurement over the telephone lines comprises amonitoring and measuring device 118 which may take the form, forexample, of an electronic thermometer, an electronic blood pressuregauge, a pulmonary function apparatus, a Doppler study apparatus, an EEGmachine, an EKG machine, an EMG machine, or a pressure measurementdevice, etc., or include a plurality of such components. Monitoring andmeasuring device 118 is connected at an output to a digitizer 120 whichin turn is coupled to a modulator 122. Modulator 122 modulates a carrierfrequency from a frequency generator 124 with the data arriving frommonitoring and measuring device 118 via digitizer 120 and transmits themodulated signal to an electroacoustic transducer 126 via an amplifier128. Transducer 126 is removably attachable via a mounting element 130to the mouthpiece of a telephone handset (not shown) and generates apressure wave signal which is converted by a microphone in the handsetmouthpiece back to an electrical signal for transmission over thetelephone lines. Of course, transducer 126 may be omitted and modulator122 connected directly to a telephone line.

The system of FIG. 7 enables the transmission of specialized medicaldata directly over the telephone lines to a central computer (e.g.computer 64 in FIG. 4) which utilizes the incoming data to perform adiagnostic evaluation on the patient.

Monitoring and measuring device 118 may include traditional medicalinstrumentation such as a stethoscope or modern devices such as a CCD.

FIG. 8 shows an ultrasonographic image generating apparatus which may beused in the medical diagnostic system of FIG. 1 (see referencedesignation 42) or in the medical diagnostic system of FIG. 4 (seereference designations 78 a, 78 b, . . . 78 i). As will be apparent fromthe following descriptions, the ultrasonographic image generatingapparatus utilizes ultrasonic pressure waves to obtain three-dimensionalstructural information pertaining to a patient's internal tissues andorgans. As shown in FIG. 8, a flexible web 132 carries a plurality ofelectromechanical transducers 134 particularly in the form ofpiezoelectric electroacoustic crystal elements disposed in asubstantially rectangular array. Transducers 134 are each connectable toan ultrasonic signal generator 136 via a switching circuit ormultiplexer 138. Switching circuit 138 is operated by a control unit 140to connect transducers 134 to signal generator 136 in a predeterminedsequence, depending on the area of a patient's body which is beingultrasonically scanned. The sequence in which transducers 134 areconnected to signal generator 136 may include phase shifts or timedelays to implement an electronic scan of the patient's internaltissues, as discussed below with reference, for example, to FIG. 32.

Web 132 also carries a multiplicity of electromechanical, specificallyacoustoelectric, transducers particularly in the form of transducers orsensors 142 also arranged in a substantially rectangular array. Sensors142 are connected to a switching circuit 144 also operated by controlunit 140. An output of switching circuit 144 is connected to a sound orpressure wave analyzer 146 via an amplifier 148.

The sequence in which sensors 142 are connected to pressure waveanalyzer 146 may be such as to enable or facilitate an organization ofsensor responses into predetermined groupings defining respective datagathering apertures. The grouping of sensors 142 may be an instantaneousgrouping, varied instant by instant pursuant to real-time imagingrequirements. Generally, the larger the apertures (the larger the areasof the respective groupings), the higher the resolution of thethree-dimensional (“3D”) volumetric data acquisition and of the imagingof the ultrasonographic system. Where the outputs of sensors 142 aresampled or interrogated in groups so as to form a plurality of datagathering apertures, control unit 140 includes coherent aperturecombining circuitry (See FIG. 29) for coherently combining structuraldata from the respective apertures. In this case, position determinationcircuitry in control unit 140 and/or sound analyzer 146 executescomputations according to a self-cohering algorithm that computes therelative positions and orientations of the data gathering aperturesusing instantaneous position measurements and adjusts the signals fromthe coherently combined apertures so they can be added togetherconstructively. The resultant effective increase in total aperture sizeimproves the resolution capability of the imaging system. Electronicscanning performed by each data gathering aperture also requiresposition determination circuitry that computes the relative positions ofthe sensors 142 themselves (since they are contained in a flexible web).Control unit 140 may also include the option of noncoherently combiningstructural data, which allows extended images to be created withoutincreasing the imaging resolution.

The sequence in which sensors 142 are connected to analyzer 146 byswitching circuit or multiplexer 144 may include phase shifts or timedelays to implement an electronic scan of the patient's internaltissues, as discussed below.

Electroacoustic transducers 134 and sensors 142 may be implemented inthe form of packaged modular arrays of piezoelectric crystals, asdiscussed hereinafter with reference to FIG. 29. At the present time,such packages are generally linear arrays of some one hundred or morepiezoelectric crystal elements. Some modified linear arrays containseveral linear arrays so that a transverse or width dimension has up toten crystal elements.

FIG. 8 shows electroacoustic transducers 134 and sensors 142 as beingseparate, so that they perform dedicated generating (i.e., transmitting)and receiving functions, respectively. It is also possible, however, toprovide a multiplicity of piezoelectric electromechanical transducers orarrays of transducer elements which perform both the transmitting andthe receiving functions. Various combinations of functions are alsopossible. For example, some transducer arrays may function as bothtransmitters and receivers, while other transducer arrays function onlyas receivers. The various operating potentialities are discussed ingreater detail below with reference to FIG. 29.

Web 132 is draped over or placed around a portion of a patient's bodywhich is to be monitored ultrasonically. Control unit 140 then energizessignal generator 136 and operates switching circuit 138 to activatetransducers 134 in a predetermined sequence. Each transducer 134 may bea multiple-element aperture. In that case, several piezoelectricelements or scalar excitation transducers are energized simultaneouslywith the excitation waveform where appropriate phases shifts or timedelays are applied to effectuate electronic scanning. Depending on thetransducer or combination of transducers 134 which are activated,control unit 140 operates switching circuit 144 to connect apredetermined sequence of sensors 142 to pressure wave analyzer 146.Again, each sensor 142 may be a multiple-element aperture, whereby aplurality of piezoelectric crystals are monitored simultaneously toreceive a reflected pressure waveform. Pressure wave analyzer 146 andcontrol unit 140 cofunction to provide electronic 3D volumetric dataacquisition and to determine three dimensional structural shapes fromthe echoes detected by sensors 142. The volumetric data acquisition isperformed by solely the electronic scanning of the three dimensionalstructural shapes.

Control unit 140 is connected to ultrasonic signal generator 136 forvarying the frequency of the generated signal. Generally, the higher thefrequency, the greater the penetration into organic tissues for focusingpurposes. Thus, a range of frequencies is useful for obtainingsufficient data to construct electrically or digitally encodedthree-dimensional models of internal tissue and organ structures of apatient.

FIG. 9 shows a modified ultrasonography web 150 having a limited numberof electromechanical or electroacoustic transducers 152 and generallythe same number and disposition of electromechanical or acoustoelectricsensors 154 as in web 132.

Web 132 or 150 may be substantially smaller than illustrated and maycorresponding carry reduced numbers of transducers 134 and 152 andsensors 142 and 154. Specifically, web 132 or 150, instead of being asheet large enough to wrap around a torso or arm of a patient, may takea strip-like form which is periodically moved during use to different,predetermined locations on the patient. Control unit 140 and pressurewave analyzer 146 are programmed to detect internal organic structuresfrom the data obtained at the different locations that the web 132 or150 is juxtaposed to the patient.

FIG. 10 illustrates a modification of the ultrasonography apparatus ofFIGS. 8 and 9 which is employable in diagnostic or therapeuticoperations involving the insertion of an instrument into a patient. Acontrol unit 156 for performing operations of control unit 140 isconnected at an output to a video monitor 158. As discussed hereinafterwith reference to FIGS. 12 and 13, a diagnostician, surgeon or othermedical specialist inserts a distal end of a medical instrument into apatient in response to video feedback provided by the ultrasonographyapparatus including video monitor 158.

As further illustrated in FIG. 10, an a-c current or ultrasonic signalgenerator 160 is connected via a multiplexer or switching circuit 162 todifferent piezoelectric type electroacoustic transducers 164 inseriatim. Transducers 164 are mounted in interspaced fashion to aflexible web 166 which also carries an array of spaced piezoelectrictype acoustoelectric transducers 168.

Web 166 is placed adjacent to a skin surface of a patient. In somecases, with any of the ultrasonic sensing devices described herein, itmay be beneficial to provide a layer of fluid (e.g., water, gel) betweenthe skin surface of the patient and the respective transducer carrier(e.g., web 166) to facilitate ultrasonic wave transmission from theelectroacoustic transducers to the patient and from the patient back tothe acoustoelectric transducers or sensors. In some specific embodimentsof an ultrasonic imaging device discussed herein, a fluid-filled bag isused to optimize pressure wave transmission between a transducer carrierand a skin surface of a patient. Another kind of interface facilitatingultrasonic wave conduction is a moldable solid or semisolid such aswave-conductive plastic material, known in the art.

In response to the periodic energization of transducers 164, ultrasonicpressure waves are reflected from internal organic structures of thepatient and sensed by acoustoelectric transducers 168. Electricalsignals generated by transducers 168 in response to the reflectedpressure waves are fed via a multiplexer or switching circuit 170 tocontrol unit 156.

As discussed hereinabove with reference to control unit 140 in FIG. 8,control unit 156 controls switching circuits 162 and 170 to energizeemitting transducers 164 in a predetermined sequence and to selectivelycouple receiving transducers 168 in a pre-established sequence to apressure wave or ultrasonic frequency analyzer 172 in control unit 156.The sequencing depends in part on the portion of the patient beingmonitored.

As further discussed above with reference to FIG. 8, the sequence inwhich receiving transducers 168 are sampled or interrogated by switchingcircuit 170 may organize sensor response into predetermined groupingsdefining respective data gathering apertures. Control unit 156 andparticularly ultrasonic frequency analyzer 172 thereof operates tocoherently combine structural data from the respective apertures, withthe execution of a self-cohering algorithm which computes the relativepositions and orientations of receiving transducers 168 (or datagathering apertures) using instantaneous position measurements and whichadjusts the signals from the coherently combined apertures so they canbe added together constructively. The sequencing of transducerenergization or excitation, as well as the sampling of outputs ofsensors, may also be carried out to execute a phased-array-typeelectronic scan of internal tissues.

In addition to pressure wave or ultrasonic frequency analyzer 172,control unit 156 includes a view selector 174 and a filter stage 176.View selector 174 is operatively connected at an input to analyzer 172and at an output to video monitor 158 for selecting an image for displayfrom among a multiplicity of possible images of the internal organsdetected by analyzer 172. View selector 174 may be provided with aninput 178 from a keyboard (not shown) or other operator interface devicefor enabling an operator to select a desired view. For example, duringthe insertion of a medical diagnostic or treatment instrument into thepatient or during manipulation of that instrument to effect an operationon a targeted internal organ of the patient, the medical practitionermay sequentially select views from different angles to optimize thepractitioner's perception of the spatial relation between the distal tipof the instrument and the patient's internal organs.

Filter stage 176 is operatively connected to analyzer 172 and videomonitor 158 for optionally eliminating a selected organ from thedisplayed image. Filter stage 176 is provided with an input 180 from akeyboard (not shown) or other operator interface device for enabling anoperator to select an organ for deletion from the displayed image. Inone example of the use of filter stage 176, blood moving through avessel of the vascular system is deleted to enable viewing of the bloodvessel walls on monitor 158. This deletion is easily effected startingfrom conventional techniques such as the Doppler detection of movingbodies.

Filter stage 176 may also function to highlight selected organs. Thepattern recognition techniques discussed above are used to detectselected organs. The highlighting may be implemented exemplarily throughcolor, intensity, cross-hatching, or outlines.

As further illustrated in FIG. 10, control unit 156 is optionallyconnected at an output to a frame grabber 182 for selecting a particularimage for reproduction in a fixed hard copy via a printer 184. Inaddition, as discussed hereinabove with respect to thetelecommunications links 80 a, 80 b . . . 80 i in FIG. 4, ultrasonicallyderived real-time image information may be encoded by a modulator 186onto a carrier wave sent to a remote location via a wireless transmitter188.

FIG. 11 depicts the ultrasonography apparatus of FIG. 10 in a formwherein control unit 156 (FIG. 10) is realized as a specially programmedgeneral purpose digital computer 190. A switching circuit or multiplexer192 relays signals incoming from respective acoustoelectric transducers168 (FIG. 10) in a predetermined intercalated sequence to ananalog-to-digital converter 194, the output of which is stored in acomputer memory 196 by a sampling circuit 198 of computer 190. A waveanalysis module 200 of computer 190 retrieves the digital data frommemory 196 and processes the data to determine three dimensional organicstructures inside a patient. This three-dimensional structural data isprovided to a view selection module 202 for deriving two-dimensionalimages for display on monitor 158 (FIG. 10). A filter module 204 isprovided for removing selected organs from the image presented on thevisual display or video monitor 158. Sampling circuit 198, wave analysismodule 200, view selection module 202, and filter module 204 areprogram-modified generic digital circuits of computer 190.

FIG. 12 shows a use of a flexible ultrasonic sensor web 206 which may beany of the flexible ultrasonic sensor webs described herein, except thatweb 206 is additionally provided with a plurality of apertures orperforations 208. Upon the placement of web 206 in pressure-wavetransmitting contact with a skin surface of a patient P, elongatediagnostic or therapeutic instruments such as laparoscopic surgicalinstruments 210 and 212 are inserted through respective openings 208 toperform a surgical operation on a designated internal organ of thepatient P1. This operation is effectuated by viewing a real time imageof the distal ends of the instruments 210 and 212 in relation to thepatient's internal organic structures as determined by control unit 156or computer 190. Generally, the image on monitor 158 is viewed duringinsertion of instruments 210 and 212 to enable a proper employment ofthose instruments. Also, the video images on monitor 158 are viewed toenable a proper carrying out of the “laparoscopic” surgical operation onthe designated internal organ of the patient P1. Strictly speaking, thisoperation is not a laparoscopic operation, since a laparoscope is notused to provide a continuing image of the patient's internal organicstructures and the distal ends of instruments 210 and 212.

There are multiple advantages to using sonographic web 206 instead of alaparoscope. Fewer perforations need be made in the patient for the samenumber of surgical instruments. In addition, multiple views of thepatient's internal organic structures are possible, rather than a singleview through a laparoscope. Generally, these multiple views may differfrom one another by as little as a few degrees of arc. Also,particularly if web 206 is extended essentially around patient P1,viewing angles may be from under the patient where a laparoscopic couldnot realistically be inserted.

Web 206 may be used to insert tubular instruments such as catheters anddrainage tubes, for example, for thoracentesis and abscess drainage. Thetubes or catheters are inserted through apertures 208 under direct realtime observation via monitor 158.

In addition to treatment, web 206 may be used to effectuate diagnosticinvestigations. In particular, a biopsy instrument 214 may be insertedthrough an aperture 208 to perform a breast biopsy, a liver biopsy, akidney biopsy, or a pleural biopsy.

As illustrated in FIG. 13, a flexible ultrasonic sensor web 216, whichmay be any of the flexible ultrasonic sensor webs described herein, maybe used in a diagnostic or therapeutic operation utilizing a flexibleendoscope-like instrument 218. Instrument 218 has a steering control 220for changing the orientation of a distal tip 222 of the instrument.Instrument 218 also has a port 224 connected to an irrigant source 226and another port 228 connected to a suction source. In addition,instrument 218 is provided a biopsy channel (not shown) through which anelongate flexible biopsy instrument or surgical instrument 230 isinserted.

Instrument 218 is considerably simplified over a conventional endoscopein that instrument 218 does not require fiber-optic light guides forcarrying light energy into a patient P2 and image information out of thepatient. Instead, visualization of the internal tissues and organstructures of patient P2 is effectuated via monitor 158 and control unit156 or computer 190. As discussed above with reference to FIG. 12, thesonographic imaging apparatus if web 216 is extended essentially aroundpatient P2, images may be provided from multiple angles, not merely fromthe distal tip 222 of instrument 218.

View selector 174 and organ filter stage 176 or view selection module202 and filter module 204 may function in further ways to facilitateviewing of internal organic structures. In addition to organ removal andhighlighting, discussed above, a zoom capability may be provided. Thezoom or magnification factor is limited only by the resolution of theimaging, which is determined in part by the frequency of the ultrasonicpressure waves. The resolution of the imaging is also determined by thesizes of various transducer arrays which function together as singleapertures. Generally, the larger the array, or the more transducerswhich are energized or sampled synchronously, then the higher theresolution. As discussed hereinafter with reference to FIG. 29 et seq.,coherent aperture combining is used to increase the sizes of thetransducer array apertures, thereby maximizing image resolution.

FIGS. 14 and 15 depict a specialized ultrasonic sensor web 232 in theform of a garment such as a vest. Sensor vest 232 has arm holes 234 and236, a neck opening 238 and fasteners 240 for closing the vest about apatient. In addition, sensor vest 232 is provided with a plurality ofelongate chambers 242 which receive fluid for expanding the vest intoconformation with a patient's skin surface, thereby ensuring contact ofthe vest with a patient's skin surface and facilitating the transmissionof ultrasonic pressure waves to and from ultrasonic transducers 244.FIG. 14 shows a computer 246, a video monitor 248 and a printer 250 usedas described above.

Sensor vest 232 may be understood as a container assembly havingfluid-filled chambers 242 with flexible inwardly facing walls (notseparately designated) which conform to the patient. Sensor vest 232 mayadditionally be provided along an inner side with a conventionalinterface medium, whether water, gel, plastic or some other material,which is conducive to the transmission of ultrasonic vibrations acrossthe interface between the patient and the sensor vest.

As illustrated in FIG. 16, an ultrasonography apparatus comprises acontainer assembly 302 including a substantially rigid plate 304attached to a flexible bladder or bag 306. Bladder or bag 306 is filledwith a liquid and is sufficiently flexible to substantially conform to apatient when the container assembly 302 is placed onto a patient PT1, asillustrated in FIG. 17. A liquid or gel or other interface medium may bedeposited on the patient prior to the placement of container assembly302 on patient PT1.

Plate 304 is provided with multiple ultrasonic pressure wave generatorsand receivers 308 as described above with respect to FIGS. 8 and 9 andFIGS. 14 and 15. Generators and receivers 308 are connected to acomputer 310 having essentially the same functional structures andprogramming as computer 190 for implementing sequential generatorenergization and sequential receiver sampling, as described above.Computer 310 is connected to a monitor 312 for displaying images ofinternal organs of patient PT1. Computer 310 has the capability ofalternately displaying organ images from different angles, as discussedabove.

Ultrasonic pressure wave generators and receivers 308 may be denselypacked and energized or interrogated as individual elements separatelyfrom each other. Coherent aperture combining is not used in such anoperating mode. Alternatively, the ultrasonic pressure wave receivers308 may be sampled or interrogated in groups, permitting the formationof a plurality of data gathering apertures. In that case, computer 310may coherently combine structural data from the different apertures tothereby increase focusing power or resolution.

Plate 304 may be formed as a rectangular array of rigid modularsubstrates rigidly connected to one another, each of the substratesholding a plurality of the transducers. The modular substrates areoff-the-shelf components such as the 1.5D transducer arrays found inconventional, premium probes, with on the order of 100 piezoelectrictransducers (or elements) disposed in a tightly packed line along alength dimension of the substrate. Inter-element spacing is typicallyone wavelength or less to support full scanning along the lengthdimension. A width dimension of a modular substrate carriessubstantially fewer (e.g. less than 10) piezoelectric transducers.Inter-element spacing along the width dimension is typically a few orseveral wavelengths. The electronic scanning of internal tissuestructures of a patient along the length dimension is performedconventionally by computer 310. Computer 310 also provides electronicscanning of internal tissue structures of a patient in the widthdimensions of the modular substrates, where the density of thetransducers is low, using a procedure unique to the present inventionwhich is described in detail hereinafter.

FIG. 18 depicts another ultrasonography apparatus useful for bothdiagnostic investigations and minimally invasive surgical operations.The apparatus comprises a container assembly 314 which includes afluid-filled sack or bag 316 for receiving a patient PT2. Sack or bag316 includes a flexible upper wall 318 which deforms to conform to thepatient PT2 upon placement of the patient onto the bag. Bag 316 issupported on two or more sides by substantially rigid walls or panels320 and 322. Panels 320 and 322 are either integral with bag 316 orseparable therefrom. Panels 320 and 322, as well as an interconnectingbottom panel 324, may be provided with multiple ultrasonic pressure wavegenerators and receivers (not shown) as described above with respect toFIGS. 8 and 9, FIGS. 14 and 15, and FIG. 16. These generators andreceivers are connected to a computer 326 having essentially the samefunctional structures and programming as computer 190 for implementingsequential generator energization and sequential receiver sampling, asdescribed above. Computer 326 is connected to a monitor 328 fordisplaying images of internal organs of patient PT2. Computer 326 hasthe capability of alternately displaying organ images from differentangles, as discussed above.

The ultrasonic pressure wave generators and receivers may be disposed ina wall panel of bag 316 or may be provided in a separate carrier 330disposable, for example, between bottom panel 324 and bag 316, as shownin FIG. 18.

Where the ultrasonic pressure wave generators and receivers may bedensely packed and energized or interrogated as individual elementsseparately from each other. Coherent aperture combining is not used insuch an operating mode. Alternatively, the ultrasonic pressure wavereceivers may be sampled or interrogated in groups, permitting theformation of a plurality of data gathering apertures. In that case,computer 326 may coherently combine structural data from the differentapertures to thereby increase focusing power or resolution.

As illustrated in FIG. 19, the ultrasonography apparatus of FIG. 19 maybe used in conjunction with a flexible web or cover sheet 332 identicalto web 132, 150, or 206 (FIG. 8, 9, or 12). Web or cover sheet 332 isoperatively connected to computer 326 for providing ultrasonicallyderived organ position and configuration data to the computer fordisplaying organ images on monitor 328. The use of web or sheet 332enables the disposition of ultrasonic wave generators and receivers in a360 arc about a patient PT3 (diagrammatically illustrated in FIG. 19),thereby facilitating image production. Where web or sheet 332 takes theform of web 206, the sheet is provided with apertures (see FIG. 12 andassociated description) for enabling the introduction of minimallyinvasive surgical instruments into the patient PT3.

As discussed above, to contact surfaces a liquid, gel or otherconductive medium is applied to facilitate ultrasonic pressure wavetransmission over interfaces.

As discussed hereinafter with reference to FIG. 20, video monitor 158(FIGS. 10, 12, and 13) or monitor 328 (FIG. 19) may take the form of aflexible video screen layer attached to web 132, 150, 166 or 206 (FIGS.8, 9, 10, 12) or web 332 (FIG. 19). This modification of theultrasonographic imaging devices discussed above is considered to beparticularly advantageous in medical diagnosis and treatment procedures.The web or substrate with the video screen is disposed on a selectedbody portion of a patient, for example, the abdomen (FIGS. 12 and 21) ora shoulder (FIGS. 22A, 22B) or knee (FIG. 23B), so that the substrateand the video screen layer substantially conform to the selected bodyportion and so that the video screen is facing away from the bodyportion.

As shown in FIG. 20, an ultrasonographic device or system comprises aflexible substrate or web 350 which carries a plurality of piezoelectricelectroacoustic transducers 352 and a plurality of piezoelectricacoustoelectric transducers (or receivers) 354. A flexible video screen356 is attached to substrate or web 350 substantially coextensivelytherewith. Video screen 356 may be implemented by a plurality of laserdiodes (not shown) mounted in a planar array to a flexible carrier layer(not separately designated). The diodes are protected by a cover sheet(not separately illustrated) which is connected to the carrier layer.Energization componentry is operatively connected to the diodes forenergizing the diodes in accordance with an incoming video signal toreproduce an image embodied in the video signal. In a video monitor, thelaser diodes are tuned to different frequency ranges, so as to reproducethe image in color. The protective cover sheet may function also todisperse light emitted by the laser diodes, to generate a morecontinuous image.

Substrate or web 350 and video screen 356 comprise an ultrasonic videocoverlet or blanket 358 which may be used with the control hardwaredepicted in FIGS. 10 and 11. Reference numerals used in FIGS. 10 and 11are repeated in FIG. 20 to designate the same functional components.

Electroacoustic transducers 352 are connected to a-c or ultrasonicsignal generator 160 for receiving respective a-c signals of variablefrequencies. Generator 160 produces frequencies which are directed tothe electroacoustic transducers 352 by switching circuit 162. Pressurewaveforms of different ultrasonic frequencies have different penetrationdepths and resolutions and provide enhanced amounts of information to adigital signal processor or computer 360. As discussed above withreference to computer 190 of FIG. 11, computer 360 is a speciallyprogrammed digital computer wherein functional modules are realized asgeneric digital processor circuits operating pursuant to preprogrammedinstructions.

As discussed above with reference to FIG. 11, switching circuit ormultiplexer 192 relays signals incoming from respective acoustoelectrictransducers 354 in a predetermined intercalated sequence toanalog-to-digital converter 194, the output of which is stored incomputer memory 196 by sampling circuit 198. Acoustoelectric transducers354 may be interrogated by multiplexer 192 and sampling circuit 198 insuch a sequence as to enable or facilitate a grouping of transducers 354to form a plurality of data gathering apertures. Waveform analysismodule 200 retrieves the digital 3D volumetric data from memory 196 andprocesses the data acquired from the internal tissue structures, therebydetermining three dimensional organic structures inside a patient.Waveform analysis module 200 includes coherent aperture combiningcircuitry (see FIG. 29) for coherently combining structural data fromthe respective apertures. Wave analysis module 200 also includesposition determination circuitry which executes computations accordingto a self-cohering algorithm that computes the relative positions andorientations of the respective apertures using instantaneous positionmeasurements and adjusts the signals from the coherently combinedapertures so they can be added together constructively. Analysis module200 may also include the option of noncoherently combining structuraldata, which allows extended images to be created without increasing theimaging resolution.

The three-dimensional structural data generated by waveform analysismodule 200 is provided to view selection module 202 for derivingtwo-dimensional images for display on video screen 256. Filter module204 serves to remove selected organs, for example, overlying organs,from the image presented on video screen 356. Sampling circuit 198, waveanalysis module 200, view selection module 202, and filter module 204are program-modified generic digital circuits of computer 360.

Computer 360 contains additional functional modules, for example, anorgan highlighter 362 and a superposition module 364. The functions oforgan highlighter 362 are discussed above with reference to organ filter176 and 204 in FIGS. 10 and 11. Organ highlighter 362 operates toprovide a different color or intensity or cross-hatching to differentparts of an image to highlight a selected image feature. For example, agall bladder or an appendix may be shown with greater contrast thansurrounding organs, thereby facilitating perception of the highlightedorgan on video screen 356. After organ filter 204 has removed one ormore selected organs from an electronic signal representing or encodingan image of internal organs, highlighter 362 operates to highlight oneor more features of the encoded image.

Superposition module 364 effects the insertion of words or other symbolson the image displayed on video screen 356. Such words or symbols may,for example, be a diagnosis or alert signal produced by a messagegenerator module 366 of computer 360 in response to a diagnosisautomatically performed by a determination module 368 of computer 360.Module 368 receives the processed image information from waveformanalysis module 200 and consults an internal memory 370 in a comparisonor pattern recognition procedure to determine whether any organ orinternal tissue structure of a patient has an abnormal configuration.The detection of such an abnormal configuration may be communicated tothe physician by selectively removing organs, by highlighting organs ortissues, or superimposing an alphanumeric message on the displayedimage. Accordingly, message generator 366 may be connected to organfilter 204 and organ highlighter 362, as well as to superposition module364. The communication of an abnormal condition may be alternatively oradditionally effectuated by printing a message via a printer 372 orproducing an audible message via a speech synthesis circuit 374 and aspeaker 376.

As discussed above, the ultrasonically derived three-dimensionalstructural information from waveform analysis module 200 may betransmitted over a telecommunications link (not shown in FIG. 20) via amodulator 378 and a transmitter 380. The transmitted information may beprocessed at a remote location, either by a physician or a computer, togenerate a diagnosis. This diagnosis may be encoded in an electricalsignal and transmitted from the remote location to a receiver 382.Receiver 382 is coupled with message generator module 366, which cancommunicate the diagnosis or other message as discussed above.

Computer 360 is connected at an output to a video signal generator 384(which may be incorporated into the computer). Video signal generator384 inserts horizontal and vertical synchronization signals andtransmits the video signal to video screen 356 for displaying an imageof internal patient organs thereon.

FIG. 21 diagrammatically depicts a step in a “laparoscopic”cholecystectomy procedure utilizing the ultrasonographic device orsystem of FIG. 20. Coverlet or blanket 358 is disposed on the abdomen ofa patient P2 in pressure-wave transmitting contact with the skin. Theskin is advantageously wetted with liquid to facilitate ultrasonicpressure wave transmission. Laparoscopic surgical instruments 210 and212 (same as in FIG. 12) are inserted through respective openings 386 incoverlet or blanket 358 to perform a surgical operation on a gallbladder GB of the patient P2. This operation is effectuated by viewing areal time image of the distal ends of the instruments 210 and 212 inrelation to the patient's internal organic structures as determined bycomputer 360. Generally, the image on video screen 356 is viewed duringinsertion of instruments 210 and 212 to enable a proper employment ofthose instruments.

As illustrated in FIG. 21, the gall bladder GB is highlighted (e.g.,with greater contrast in screen intensities) relative to other organssuch as the liver LV, the stomach ST and the large intestine LI. One ormore of these organs may be deleted entirely by organ filter 204.Computer 360 is instructed as to the desired display features via akeyboard (not illustrated in FIG. 20) or a voice recognition circuit 388operatively connected to various modules 202, 204 and 362. (It is to benoted that speech synthesis circuit 374 and voice recognition circuit388 enable computer 360 to carry on a conversation with a user. Thus theuser may direct the computer to answer questions about the appearance ofcertain organs selected by the user.)

Generally, the images of the different organs GB, LV, ST and LI, etc.,are displayed on video screen 356 so as to substantially overlie theactual organs of the patient P2. To effectuate this alignment of imageand organ, markers 390, 392, 394 are placed on the patient P2 atappropriate identifiable locations such as the xyphoid, the umbilicus,the pubis, etc. The markers are of a shape and material which are easilydetected by ultrasonic wave analysis and provide computer 360 with areference frame for enabling the alignment of organ images on screen 356with the corresponding actual organs. During an operation, view selector202 may be utilized (via keyboard command or voice recognition circuit388) to adjust the relative positions of image and organs to facilitatethe performance of an invasive surgical operation. As discussed abovewith reference, for example, to FIG. 13, the ultrasonographic device orsystem of FIG. 20 may be used in other kinds of procedures.

As illustrated in FIG. 22A, an ultrasonographic coverlet or blanket 396with attached video screen (not separately designated) and connectedcomputer 398 has a predefined shape conforming to a shoulder SH. Thecoverlet or blanket 396 is flexible and thus deforms upon motion of theshoulder (FIG. 22B). The coverlet or blanket 396 has a memory so that itreturns to the predefined shape when it is removed from the shoulder SH.The flexibility of the coverlet or blanket 396 enables the display inreal time of a filtered video image showing the shoulder joint SJ duringmotion of the shoulder. This facilitates a diagnostic appraisal of thejoint.

FIG. 23A illustrates an ultrasonic video cuff 400 with a computer 402.The cuff is attachable in pressure-wave transmitting contact to a kneeKN, as depicted in FIG. 23B. Cuff 400 conforms to the knee KN andfollows the knee during motion thereof. A knee joint KJ is imaged on thecuff during motion of the knee KN, thereby enabling a physician to studythe joint structure and function during motion. Cuff 400 has a memoryand returns to its predefined shape (FIG. 23A) after removal from kneeKN.

Video screen 356, as well as other video monitors disclosed herein, maybe a lenticular lens video display for presenting a stereographic imageto a viewer. The ultrasonic processor, e.g., computer 190 or 360,operates to display a three-dimensional image of the internal organs onthe lenticular lens video display. 118. Because of the stereoscopicvisual input a surgeon is provided via video display 356, he or she isbetter able to manipulate instruments 210 and 212 during a surgicalprocedure.

Electroacoustic transducers 134, 164, 352 in an ultrasonographiccoverlet or blanket 132, 166, 206, 216, 358 as described herein may beused in a therapeutic mode to dissolve clot in the vascular system. Thecoverlet or blanket is wrapped around the relevant body part of apatient so that the electroacoustic transducers surround a target veinor artery. First, a scan is effectuated to determine the location of theclot. Then, in a clot dissolution step, the electroacoustic transducersare energized to produce ultrasonic pressure waves of frequenciesselected to penetrate to the location of the clot. With a sufficientlylarge number of transducers transmitting waves to the clot sitesimultaneously, the clot is disrupted and forced away from the clotsite. It is recommended that a filter basket be placed in the pertinentblood vessels downstream of the clot site to prevent any large clotmasses from being swept into the brain or the lungs where an embolismwould be dangerous.

The monitors disclosed herein, such as monitors 158, 248, 312, 328 andvideo screen 356, may be provided with a lenticular lens array (notshown) for generating a three-dimensional or stereoscopic display imagewhen provided with a suitable dual video signal. Such a dual signal maybe generated by the waveform analysis computer 190, 310, 326, 360 withappropriate programmed for the view selection module 202 to select twovantage points spaced by an appropriate distance. Lenticular lens videodisplays, as well as the operation thereof with input from two cameras,are disclosed in several U.S. patents, including U.S. Pat. No. 4,214,257to Yamauchi and U.S. Pat. No. 4,164,748 to Nagata, the disclosures ofwhich are hereby incorporated by reference.

It is to be noted that any of the ultrasonography devices or systemsdisclosed herein may be used in a robotic surgical procedure wherein oneor more surgeons are at a remote location relative to the patient. Theperformance of robotic surgery under the control of the distant expertsis disclosed in U.S. Pat. Nos. 5,217,003 and 5,217,453 to Wilk, thedisclosures of which are hereby incorporated by reference. Video signalstransmitted to the remote location may be generated by the analysis ofultrasonic waves as disclosed herein.

The ultrasonography devices or systems disclosed herein may be used inconjunction with other kinds of scanning devices, for example, spectraldiagnosis and treatment devices described in U.S. Pat. Nos. 5,305,748 toWilk and 5,482,041 to Wilk et al. (those disclosures incorporated byreference herein). It may be possible to incorporate the electromagneticwave generators and sensors of those spectral diagnosis and treatmentdevices into the coverlet or blanket of the present invention.

As illustrated in FIG. 24, a medical imaging device comprises a planarfirm substrate 404, a substantially flat video screen 406 provided onthe substrate, and a flexible bag 408 connected to the substrate.Flexible bag 408 contains a fluidic medium such as water or gel capableof transmitting pressure waves of ultrasonic frequencies and is disposedon a side of the substrate opposite the video screen. Alternatively andequivalently, bag 408 may be a substantially solid mass of a deformablematerial conducive to the transmission of ultrasonic pressure waves.Certain plastic or polymeric materials known in the art would besuitable for such an application. As discussed above, a scanner 410including an ultrasonic waveform generator 412 and acomputer-implemented ultrasonic signal processor 414 are operativelyconnected to video screen 406 for providing a video signal thereto. Thevideo signal encodes an image of internal tissues of a patient PT4 uponplacement of medium-containing bag 408, substrate 404, and video screen406 against the patient. The images of internal tissues and organs offthe patient, including the stomach SH, the heart HT, the lungs LG, thesmall intestine SE, and the large intestine LE, are displayed on screen406 at positions generally overlying the respective actual tissues andorgans of the patient PT4.

Video screen 406 and substrate 404 may be provided with alignedapertures 415 for enabling the traversal of the video screen and thesubstrate by medical instruments as discussed above with reference toFIG. 21.

FIGS. 25 and 26 show another medical imaging device comprising aflexible bag 416 containing a fluidic medium such as water or gel. Amultiplicity of substantially rigid planar substrates or carrier pads418 together with respective flat video screens 420 attached thereto aremounted to an upper surface of bag 416. Bag 416 serves in part tomovably mount pads 418 with their respective video screens 420 to oneanother so that the orientations or relative angles of the video screencan be adjusted to conform to a curving surface of a patient PT5, asshown in FIG. 26. Again, a scanner 422 including an ultrasonic waveformgenerator 424 and a computer-implemented ultrasonic signal processor 426is operatively connected to video screens 420 for providing respectivevideo signals thereto. The video signals encode respective images ofinternal tissues of a patient PT5 upon placement of medium-containingbag 416, substrates 418 and video screens 420 against the patient. Asillustrated in FIG. 27A, the video images displayed on screen 420 may besubstantially the same, with differences in the angle of view of atarget organ ORG, depending on the locations and orientations of therespective screens 420. Alternatively, in an enlarged view, a singleimage of the target organ ORG may be displayed, with each screen 420displaying only a part of the total image. The technology forimplementing these displays over video screens 420 is conventional andwell known.

Scanners 410 and 422 are ultrasonic scanners with the same components asother ultrasonic scanners discussed herein, for example, with referenceto FIG. 21. Briefly, scanners 410 and 422 each includes a plurality ofelectroacoustic transducers and a plurality of acoustoelectrictransducers disposed in respective arrays in the respective bag 408 or416 or on substrates 404 and 418 so that ultrasonic pressure waves cantravel through the fluidic medium in the respective bag from theelectroacoustic transducers and to the acoustoelectric transducers.Computers or processors 414 and 426 analyze incoming digitizedultrasonic sensor signals which are produced in response to ultrasonicpressure waves reflected from various tissue interfaces in the patientPT4 or PT5. From these incoming ultrasonic sensor signals, computers orprocessors 414 and 426 determine three-dimensional shapes of tissueinterfaces and organs inside the patient PT4 or PT5.

Accordingly, scanners 410 and 422 include electromechanical transducers,specifically electroacoustic and acoustoelectric transducers (neithershown), as discussed herein for generating ultrasonic pressure waves andreceiving or detecting reflected pressure waves as discussedhereinabove. The transducers may be mounted to carrier plates orsubstrates 404 and 418, may be incorporated into flexible bags 408 and416, or may be disposed in carrier panels underlying the patient asdescribed hereinabove with reference to FIGS. 18 and 19. As discussedbelow with reference to FIG. 29 et seq., the transducers are possiblyincorporated into rigid arrays functioning as respective apertures whosesignal outputs may be coherently combined to maximize resolution.

The transducers of scanners 410 and 422 may be densely packed in bothlength and width dimensions using inter-element spacings, in both thelength and width dimensions, of a wavelength or less to support full 2Dscanning. Alternatively, presently available, off-the-shelf 1D or 1.5Darray technology may be used. Processors 414 and 426 may organize thetransducers contained within substrates 404 and 418 into groups or datagathering apertures and coherently combine structural data from theapertures, using CAC, to enhance the attainable resolution. Aself-cohering algorithm is not needed in this case since all aperturelocations and orientations are known. Within each data gatheringaperture, electronic scanning is effectuated to interrogate tissuestructures. For the case where data gathering apertures are to becombined from different substrates, a self-cohering algorithm is neededto process the data from the respective apertures in the embodiment ofFIGS. 25 and 26.

As discussed above with reference to FIG. 21, it is recommended thatmarkers be placed in prespecified locations on the patient to enable orfacilitate an alignment of the displayed tissue representations and therespective underlying actual tissues. The markers are easily recognizedby computer 426 and serve to define a reference frame whereby thepositions and the orientations of the multiple video screens 420relative to the patient's internal tissues are detectable. Thus, theposition and the orientation of each video screen 420 relative to theinternal tissues and organs of the patient PT5 are determined to enablethe display on the video screens 420 of images of selected targettissues of the patient. The reference markers facilitate the display onscreens 420 of respective views of the same organ or tissues fromdifferent angles depending on the positions and orientations of thevarious screens 420.

As discussed above, for example, with reference to FIGS. 20 and 21,computers or processor 414 and 426 may include a module 362, typicallyrealized as a programmed general computer circuit, for highlighting aselected feature of the internal organs of patient PT4 or PT5. Thehighlighting is achievable by modifying the color or intensity of theselected feature relative to the other features in the displayed image,thus providing a visual contrast of the selected feature with respect tothe other features of the displayed image. An intensity change may beeffectuated by essentially blacking or whiting out the other portions ofthe image so that the selected feature is the only object displayed onthe video screen.

The imaging devices of FIGS. 24 and 26 are optionally provided with avoice-recognition circuit 388 and a speech synthesis circuit 374 (FIG.20) operatively connected to computer or processor 414 and 426.Advantages and uses of these components are discussed above withreference to FIG. 20. As further described above, computers orprocessors 414 and 426 are possibly programmed for automated diagnosisbased on pattern recognition, with the computed diagnosis beingcommunicated to the user physicians via speech synthesis circuit 374.

As illustrated in FIG. 28, the imaging device of FIGS. 26 and 27 isadvantageously provided with a plurality of apertures or passageways 428extending through bag 416 in the interstitial spaces between videoscreens 420. Passageways 428 receive respective tubular cannulas 430which extend both through the passageways and respective openings (notshown) in the skin and abdominal wall of the patient PT5. Medicalinstruments such as a laparoscopic forceps 432 are inserted throughpassageways 428 for performing an operation on internal target tissuesof patient PT5 essentially under direct observation as afforded by videoscreens 420. The distal ends of the medical instruments 432, insertedinto patient PT5 in the field of view of the imaging system, aredisplayed on one or more video screens 420 together with internal targettissues of the patient. The uses of the imaging device of FIGS. 25 and26 with passageways 428 as illustrated in FIG. 28 are substantiallyidentical to the uses and modes of operation described above withreference to FIGS. 20 and 21.

It is to be noted that bag 416 may be replaced by a plurality of bags(not illustrated) all filled with a fluidic medium through whichultrasonic pressure waves may be transmitted. Each planar substrate orcarrier pad 418 and its respective video screen may be attached to arespective fluid-filled bag. In this modification of theultrasonographic device of FIGS. 25 and 26, apertures performing thefunction of passageways 428 (FIG. 28) are naturally formed as gaps orspaces between adjacent bags. Separate coupling elements (notillustrated) must be provided between adjacent video screens 420 forforming an integral structure while enabling at least limited flexingbetween adjacent video screens 420.

It is to be additionally understood that substrates 418 may be formed ascarrier layers for active picture elements of video screens 420 and maybe visually indistinguishable from the video screens 420.

The imaging devices of FIGS. 24 and 25, 26 may include a transmitter 380and a receiver 382 (FIG. 20) for operatively connecting scanners 410 and422 and particularly computers or processors 414 and 426 to along-distance hard-wired or wireless telecommunications link. As pointedout above, image data transmitted over the telecommunications link to avideo monitor at a remote location will enable observation of thepatient's internal tissues by distant specialists who may also operateon the patients robotically via the telecommunications link.

Where the imaging device of FIGS. 25-28 is used to diagnose or treat alimb or a joint, planar substrates 418 and video screens 420 have sizesand two-dimensional shapes which facilitate substantial conformity withthe limb or joint. To facilitate the use of the imaging device ininvasive surgical procedures, the images provided on video screens 420may be stereoscopic or holographic. Thus, manipulation of medicalinstrument 432 so that its distal end engages desired internal tissuesis facilitated. The imaging device thus may include elements forproviding a stereoscopic or holographic image to a viewer, the scannerincluding means for energizing the elements to produce the stereoscopicor holographic image.

As illustrated in FIG. 29, another ultrasonic imaging system comprises aflexible substrate or web 434 carrying a plurality of modularoff-the-shelf transducer packages 436 disposed in a substantiallyrectangular array. Each package 436 comprises a rigid substrate 437 towhich is mounted a multiplicity of piezoelectric crystal transducerelements 438. Transducer elements 438 are all electromechanical and maybe termed “electroacoustic” in the case of excitation or transmission ofultrasonic pulses and “acoustoelectric” in the case of reception orsensing of a reflected ultrasonic pulses. Transducer packages 436 mayincorporate an arrangement of one or more off-the-shelf hardwarecomponents such as conventional 1D and 1.5D arrays as describedelsewhere herein, or may be made up of an arrangement (e.g. a 1D or 2Darray) of scalar transducer elements.

As discussed above, web 434 may be provided with or on a fluid-filledflexible bag (not shown) for enhancing ultrasonic coupling with a curvedsurface such as a patient. Other measures may be utilized forfacilitating ultrasonic pressure wave transmission from and to thetransducer elements 438 of the various modular transducer packages 436.

Generally, it is contemplated that the piezoelectric crystal elements438 of any given package 436 are energized simultaneously in excitationand reception to effectuate the scanning of an acoustic beam used tointerrogate the desired tissue. Thus, each transducer package 436functions as a single data gathering aperture. The purpose of thistechnique is to enhance image resolution over currently available 1D and1.5D array transducers, and to provide electronic 3D volumetric dataacquisition. Further enhancement is achieved by coherent aperturecombining, discussed below.

Piezoelectric crystal elements 438 are energized by ultrasonicelectrical excitation waveforms produced by a signal generator 440 inresponse to signals from an acquisition controller 442. (Datatransmission paths are indicated in FIG. 29 by solid line arrows, whilecontrol signal links are indicated in dot-dash lines.) The excitationwaveforms from signal generator 440 are directed to selected packages orapertures 436 by a switching circuit or multiplexer 444 in response tocontrol signals from acquisition controller 442. The excitationwaveforms are of variable frequency, determined on a continuing basis byacquisition controller 442 and more particularly by a frequencydetermination module 476 thereof, for optimizing image resolution atdifferent depths (range) into the patient (for example, to obtain auniform resolution along all coordinate axes). Generally, the higher thefrequency, the greater the depth or penetration of effective dataacquisition.

The excitation waveforms are generally transmitted as single pulses ofshort duration, or bursts of several pulses sent and received one afterthe other. Any one pulse may be directed to a single package or aperture436 (single aperture excitation) or to multiple packages or apertures436 simultaneously (multiple aperture excitation). Similarly, signalreception may occur using a single aperture at a given time, or usingmultiple apertures simultaneously.

Multiplexer 444 is connected to a receiver 446 and is responsive toacquisition controller 442 for selectively connecting the transducerelements 438 of packages or apertures 436 to the signal generator andthe receiver. Receiver 446 dynamically focuses incoming signals toproduce a number of vectors (range lines) of image data. To that end,receiver 446 incorporates demodulation circuits (not separately shown)to obtain coherently the received signals. It is to be noted thatmultiplexer 444 may be disposed in whole or in part on web 434.Alternatively, the multiplexer may be located at a workstation.

When different packages (or sets of packages) are used for transmissionand reception, the operating mode is termed “bistatic operation.” Whenthe same package (or set of packages) is used for transmission andreception, the operating mode is termed “monostatic operation.”

The coherent aperture combining module 488 can be used to increase theeffective size of the data gathering apertures employed, therebyincreasing image resolution. CAC can be performed using monostatic orbistatic operation. For bistatic operation, a given pulse istransmitted, for example, from one aperture, and received simultaneouslyfrom two (or more) apertures. The transmit aperture could be one of thetwo (or more) apertures used for reception. The receiver 446 processesthe signals received from both apertures and produces two respective,complex output images. For monostatic operation, two (or more) pulsesare needed. On pulse one, aperture one is used for transmission andreception. On pulse two, aperture two is used for transmission andreception. In this case, the receiver 446 produces two respectivecomplex output images, but they pertain to two different times (i.e. thetwo times associated with the two pulses). The monostatic operating modehas the disadvantage of possible phase shifts in data received by thesecond transducer array or aperture, as compared with data received bythe first transducer array or aperture, due to a different tissuescattering geometry, and different data collection times.

The coherent aperture combining module 448 provides its coherentlycombined data to an image processor 450.

Image processor 450 utilizes the increased resolution data from module448 (if CAC is performed) to perform 3D image processing, whichincludes, as special cases, 1D and 2D image processing as well. 3D imageprocessing can be used to construct three-dimensional models or analogsof internal tissue structures of a patient during a real time scanningoperation. As discussed above with reference to other embodiments of anultrasonic imaging system, an image is constructed by image processor450 pursuant to instructions entered by a user via a keyboard 452 orother input device and received by a command and control unit 454. Theconstructed image is displayed on a monitor 456 by command and controlunit 454.

During a diagnostic or treatment procedure utilizing the system of FIG.29, a user requests an image of a particular organ via input device orkeyboard 452. Command and control unit 454 interprets the request andrelays the interpreted request to acquisition controller 442. Controller422 queries image processor 450 to determine whether an image of therequested organ is already stored in an internal memory (not shown) ofthe image processor. If the data is already obtained or is obtainablevia interpolation, image processor 450 constructs the requested image,which is then passed to monitor 456 via command and control unit 454. Ifthe data required for imaging the requested organ is not in memory,acquisition controller 442 determines which transducer packages orapertures 436 must be excited and which transducer apertures 436 must beused for reception in order to obtain sufficiently high resolution datato form an image of the requested organ structure. Pursuant to itsdetermination, acquisition controller 442 activates signal generator440, multiplexer 444, and receiver 446 to implement the acquisition ofthe requisite data. Prior to data collection, acquisition controller 442accesses a calibration unit 458 to determine whether a calibrationsequence is needed. If so, acquisition controller 442 activates signalgenerator 440, multiplexer 444 and receiver 446 to conduct an ultrasonicscan for purposes of determining the locations and orientations of thevarious packages or apertures 436 relative to each other.

Calibration is effectuated by one or both of two techniques. The firsttechnique utilizes acoustic point scatterers 460 (FIG. 30) such as AIUMphantoms disposed on packages or apertures 436. Basically, transducerpackages or apertures 436 are activated under the control of acquisitioncontroller 442 to obtain position data on the various point scatterers460, while module 448 executes a self-cohering algorithm to determinethe exact relative positions of the point scatterers, therebydetermining the locations and orientations of substrates 437. It iscontemplated that phantoms could be embedded in web 434 so that asufficient number of point scatterers are always in the image field ofthe group of apertures requiring registration. The calibration data maybe acquired bistatically (using a single pulse) or monostatically (usingtwo or more pulses), as described above.

FIG. 31 is a diagram illustrating geometric parameters in the firstcalibration technique. Two point scatterers or AIUM phantoms are locatedat points A and B while transducer arrays or apertures 462 and 464 arecentered at points E and F. Transducer array or aperture 464 is rotatedthrough an angle EAF and translated a distance AF-AE from the positionof transducer 462. To register transducer 464, it is necessary todetermine angle EAF and distances AF and AE.

Distances FG, FH, GA, and HB are measured from data produced bytransducer array or aperture 464, while distances ED, EC, DA, and CB aremeasured using data generated via transducer array or aperture 462.Lengths b, c, and d are easily calculated next. Then, angle DAG iscomputed. Subsequently, angles EAD and GAF and lengths AE and AF aredetermined. Angle EAF equals angle EAD plus angle DAG plus angle GAF.(EAF=EAD+DAG+GAF.) The key to these computations is to recognize thatthe length of the vector joining two point scatterers is invariant undercoordinate system translations and rotations and hence will be measuredthe same from both transducer array or apertures 462 and 464.

Assuming significant signal-to-noise ratios, the cross-rangemeasurements are as good as the apertures can provide, i.e., one picksthe vector position where each point scatterer has maximum intensity.Azimuthal centroiding can be used to further improve the cross-rangeaccuracy, depending on the size and orientation of the point scatterersrelative to the cross-range resolution of the arrays. To obtain suitablecoherent aperture combining results, the range measurements need to beaccurate to the array focusing precision, which is better than 10microns for premium systems. With sufficient signal-to-noise ratios,such accuracies can be achieved by range over sampling (i.e., using thehighest A/D sampling rate available) combined with range centroidingtechniques. In addition, the point scatterers could also be fabricatedin pairs (or triplets, etc.) so that their separations are preciselyknown, which will assist in making the resulting positioning informationmore accurate.

Pursuant to the second calibration technique, a direct-pathself-cohering algorithm is used. A calibration or reference array oraperture receives a pulsed signal from two or more arrays, whosepositions and orientations are to be calibrated relative to each other.The reference array is disposed generally on one side of a patient'sbody while the arrays to be calibrated are disposed on another side ofthe body. In a given transverse plane through the patient and acircumferentially extending array of transducer apertures 436 , thelocations of two points on each array are needed to position and orientthe array. (In a more general procedure, the locations of three pointson each transducer must be determined.) Solving for the position of agiven point on a given array is a triangulation process using two halfapertures of the reference array. The two points (or phase centers) oneach array correspond to two sub-apertures with a high enough F# inazimuth and elevation to ensure that the calibration array is in theimage field. Let each sub-aperture transmit a pulse (or two pulses insequence if array element access is not available) and let thecalibration array receive and process the pulse(s) in each of the twosub-apertures. By measuring the range difference between the two, theposition of the array point can be computed relative to the referencearray. It is to be noted that this description assumes that thereference array and the arrays to be calibrated are nominally in thesame elevation plane. The process is repeated for all transducer arraysor apertures 436 that are to be positioned relative to each other. Ifall of the arrays in the plane are to be calibrated, then differentarrays take turns being the calibration array. Having multiplecalibration arrays also allows estimates from different calibrationarrays to be averaged, perhaps making the process more robust todeviations from planarity.

Accordingly, in the second calibration technique, the positions of aplurality of preselected phase centres (associated with subaperturesformed using a number of transducer elements 438) are determined foreach package or aperture 436 required to image the requested organstructure, thereby specifying the location and orientation of thoserequisite packages or apertures 436. The preselected phase centres aresequentially or separately energized with at least one pulse of apredetermined frequency. At least one preselected transducer array,package or aperture 436 is then polled or sampled using twohalf-apertures to sense incoming ultrasonic pressure waves of thepredetermined frequency transmitted directly (unreflected, althoughperhaps refracted) through the internal tissues of the patient. Ofcourse, bistatic operation and access to individual transducer elementsin an array (i.e. to form the two half-apertures) are required for thiscalibration procedure to work. The array element access requirementcould be eliminated by building reference arrays that consist of twoelements joined rigidly (i.e., with known, fixed separation).

The calibration procedure may be performed at regular intervals, with aperiodicity determined inter alia by such factors as the target regionin the patient, the purpose of the imaging process, and the processingcapacity of image processor 450. For example, image data collection fora target region in or near the heart should be updated more frequentlythan image data collection for a target region in a quiescent limb.Generally, therapeutic invasions require continuous monitoring to ahigher degree than diagnostic procedures.

It is to be noted that calibration may alternatively be effectuated byan auxiliary or external sensing system different from transducer arraysor apertures 436. These alternative registration systems are notconsidered germane to the present invention and are not consideredherein.

Coherent aperture combining as implemented by module 448 is anapplication of techniques known in the transmission and reception ofwireless signals, including electromagnetic radiation of variousfrequencies, as in the field of radar. Antenna array principles arestraightforwardly applied to a medical imaging system in order toimprove the spatial resolution provided by extant ultrasound arrayapertures. In general, the larger the combined aperture, the better thelateral resolution.

The ultrasonic imaging systems disclosed herein include appropriatehardware and software (not illustrated) for signal amplification,analog-to-digital conversion, and focusing. The advantageousness ofthese functions, as well as the elements required to perform thesefunctions, are well known in the conventional ultrasound arts and arenot belabored herein.

FIG. 32 depicts transducer hardware which can be used in place of or asa component of web 434 of FIG. 29. A multiplicity of off-the-shelftransducer packages or apertures 466 are rigidly connected to each otherin a rectangular array to form an ultrasonic sensor platen 468. Thisplaten or transducer carrier 468 can be used as a component in any ofthe systems described above. More particularly, the platen can be usedas a component in the construction of web 206 in FIG. 12, web 216 inFIG. 13, sensor web 232 in FIGS. 14-15, plate 304 in FIGS. 16-17, panels320, 322 and 324 in FIGS. 18-19, cover sheet 332 in FIG. 19, web 350 inFIG. 20, blanket 358 in FIG. 21, blanket 396 in FIG. 22A, cuff 400 inFIG. 23A and FIG. 23B, substrate 404 in FIG. 24 and substrates 418 inFIGS. 25-26. Pursuant to some of those systems, platen or transducercarrier 468 is provided with a fluid-filled flexible bag (e.g. 306 inFIG. 18; 316 in FIGS. 18 and 19) disposable in contact with the patientfor facilitating transmission of pressure waves into the patient fromtransducer packages or apertures 466 and transmission of reflectedpressure waves from the patient to receiving transducer packages orapertures 466.

The transducer packages 466 (in platen 468) use 1.5D transducer arraytechnology found in conventional, premium probes. This technologyemploys piezoelectric crystal elements (not shown) whose size along thelength dimension is one-wavelength or less, whereas, the size along thewidth dimension is typically several wavelengths. Each transducerpackage 466 contains on the order of 100 elements, tightly packed, alongthe length (or azimuth) dimension, and only a few (usually less than 10)elements, also tightly packed, along the width (or elevation) dimension.Due to the fine spacing along the length dimension, each transducerpackage can be electronically scanned in azimuth; however, in aconventional probe, no scanning is performed in elevation. A uniquefeature of the present invention is the ability of platen 468 to scan inelevation as well as azimuth using conventional transducer elementtechnology as described above. While full 2D electronic scanning is wellunderstood if the transducer elements are one-wavelength or less in boththe length and width dimensions (and in which case many, many moreelements will be needed to tightly pack a specified-size, 2D platen, andsimilarly, many more receiver channels will also be required, addingdramatically to the cost and practicality of such a platen), 2D scanningusing transducer elements whose feature size is large in the widthdimension (as is used herein) is not understood and a unique approach isdescribed below in support of the present invention. As described above,electronic scanning (using phased-array signal processing circuitry) isconfined to a data gathering aperture. Platen 468 can be organized intoone or more data gathering apertures where each data gathering apertureis capable of 2D scanning; and hence, provides electronic 3D volumetricdata acquisition of the tissue structures in the imaging field (i.e.below the skin surface in acoustic contact with the aperture). Theacquisition controller 442 (FIG. 29) is provided with phased-arraysignal processing circuitry 470 for effectuating the 2D electronicscanning of the internal tissue structures associated with each datagathering aperture.

As illustrated in FIG. 33, phased-array signal processing circuitry 470includes a TX timing module 472 operatively connected to multiplexer orswitching circuit 444 for calculating a set of time delays or phases ofelectrical signals to be sent to the different transducer packages orapertures 466 to effectuate a 2D electronic scan of internal tissuestructures of a patient by outgoing pressure waves (i.e. ontransmission). The multiplexer or switching circuit 444 imparts the timedelays or phases so computed. Thus, the variations in the time delays orphases of electrical signals sent to the different transducer packagesor apertures 466 is effectuated in part by multiplexer or switchingcircuitry 444 under the control of acquisition controller 442 and moreparticularly in response to control signals from module 472 ofphased-array signal processing circuitry 470.

As further illustrated in FIG. 33, phased-array signal processingcircuitry 470 further includes an RX timing module 474 operativelyconnected to multiplexer 444 and receiver 446 and which computes timedelays or phases to be used to for effectuating a 2D electronic scanningof incoming reflected pressure waves by transducer packages or apertures466. The application of the computed time delays or phases to thereceived signals is typically performed in the receiver 446 although itcould be distributed between the multiplexer 444 and the receiver 446.

The phased-array signal processing circuitry 470 performs azimuth (i.e.in the length dimension) electronic scanning in a conventional-likemanner. If a data gathering aperture employs a single, off-the-shelf,transducer array, then azimuth scanning (using sequential scanningtechniques for a linear array or phased-array scanning for aphased-array) is performed conventionally. If two or more transducerarrays make up the length dimension of the data gathering aperture toform a larger effective aperture, then a straightforward extension ofconventional azimuth scanning is applied so that the signals receivedfrom each transducer array can be coherently added (in the multiplexer444 or receiver 446) to effect scanning from the larger effectiveaperture. If scalar transducer elements are employed in the platen 468rather than transducer arrays, again, a straightforward application ofconventional scanning techniques can be applied to effectuate azimuthscanning because the locations of all scalar elements are known.

The phased-array signal processing circuitry 470 performs elevation(i.e. in the width dimension) electronic scanning in a non-conventionalmanner, although conventional principles are applied in terms of thebeam focussing techniques used to focus a given voxel (i.e. the imagelocation in the 3D volumetric region being interrogated). This elevationscanning will now be described using as an example the case where thetransducer packages 466 used in platen 468 are 1.5D array substrates,each containing on the order of 100 elements in the length dimension,and say seven elements in the width. In practice, elevation scanning isnot performed with probes containing 1.5D arrays. A typical probe mayhave a width dimension of say 1 cm and a length dimension of say 4 cm.When the probe is at a given location, an image slice can be acquiredwhich is typically about 1 mm thick in the elevation or width dimension,and 4 cm long in the azimuth or length dimension. The length of theslice in the depth dimension, D cm, relates to the depth interval in thetissue that is being interrogated. The 1 mm thick image slice is movedmanually by the operator's hand in the elevation dimension. That is, theoperator manipulates the probe by moving it in the elevation dimension,which in turn moves the image slice in a continuous fashion in theelevation dimension. Consider now the case where platen 468 containsfour 1 cm by 4 cm array substrates stacked in the width dimension sothat the platen dimension is 4 cm by 4 cm, and assume that a single datagathering aperture is formed from the four substrates contained withinthe platen. If conventional scanning techniques are appliedindependently to each substrate, then four 1 mm by 4 cm by D cm imageslices can be obtained. Although these slices do indeed span a volume(i.e. one could argue that electronic 3D data acquisition is provided),the volume is not useful in practice because there are large gaps (i.e.9 mm in width) of volumetric data that are missing between adjacentsubstrates. Whereas the total spanned volume is 4 cm×4 cm by D cm, only10% of that volume can be electronically acquired. Although individualsubstrates cannot electronically scan a full set of scanning angles inthe elevation dimension due to the large size of the width dimension ofthe scalar transducer elements (i.e. several wavelengths), a smallamount of electronic scanning, as much as +/−10 deg., is achievable(although not needed nor used in practice with 1.5D probes) withoutsuffering grating lobes or reduction in gain due to the directivity ofthe scalar element pattern response. This elevation scanning capabilityis exploited by phased-array signal processing circuitry 470 to fill inthe gaps in coverage that would otherwise result, thereby trulyproviding electronic 3D volumetric data acquisition.

Pursuant to the example in the preceding paragraph, phased-array signalprocessing circuitry 470 is programmed to provide full, electronic 3Dvolumetric data acquisition. Any given transducer substrate can bescanned upwards or downwards exemplarily 0.1 radians in the elevationdimension by applying appropriately computed time delays to the sevenelements in the width dimension. It will now be explained how thisphased array scanning accommodates or compensates for the 9 mm gap inthe width dimension contained between two adjacent substrates. At adepth of 5 cm, the beam scanned upwards from the lower substrate willintersect the beam scanned downwards by the upper substrate, therebyproviding full coverage (i.e. completely filling in the gap) for depthsgreater than five centimeters. The same coordinated approach is usedbetween other adjacent substrates to acquire the complete 3D volume fordepths greater than 5 cm. Gaps for nearer-in depths are filled bytreating the collection of scalar elements contained in the widthdimension of the data gathering aperture (at a given location along thelength of the data gathering aperture) as a single array, and usingappropriate subapertures depending on the width interval beinginterrogated. One can appreciate that by designing a subaperture so thatits phase centre is sufficiently close to the gap in question willinsure that the gap can be filled in (i.e. interrogated by thesubaperture). The subaperture approach also has the advantage that aninstantaneous aperture larger than the width dimension (1 cm in thisexample) of each substrate can be used to increase the elevationresolution, which is highly desirable in many applications.

While the above presentation illustrates the practical electronic 3Dvolumetric data acquisition capability of phased-array signalprocessing, the particular scanning methods illustrated are not intendedto limit the scope of the 2D electronic scanning capabilities of platen468. For example, one could view all of the transducer elements providedwithin a data gathering aperture as addressable elements of a 2D phasedarray. Therefore, joint 2D phased array scanning can be performed ratherthan the factored azimuth and elevation scanning approaches discussedthroughout. Clearly, these more general approaches are contemplated aswithin the scope of operation of phased-array signal processingcircuitry 470.

Additional, unique, and unconventional features of the phased-arraysignal processing circuitry 470 are provided as described hereinafter(with reference to the example just previously described), when theacquisition time of the 3D volumetric data must be minimized. It is wellunderstood that to image a moving organ such as the heart, the totalacquisition time should be on the order of 30 ms or less. Considering adepth of 15 cm, the two-way, time-of-flight of each transmitted pulse isapproximately 0.2 ms. For the transducer array of the above example with100 elements in the length dimension, the azimuth acquisition time(assuming 100 vectors and one pulse per vector) is 20 ms. If multiplereceive beams (vectors) are formed from each transmit pulse (a factor of3 is common in practice), then the azimuth acquisition time can bereduced to about 7 ms. However, if a linear transducer array (i.e. alinear data gathering aperture) is formed containing say 1000 elementsalong the length dimension, at least 70 ms is then needed to acquire the2D image slice. In this case, unconventional electronic scanning (asdescribed hereinafter) is needed to reduce the acquisition time. Thesituation is compounded further when 3D volumetric data acquisition isperformed. If a full 2D array containing 100 elements closely spaced ineach of the length and width dimensions is used, then about 33 pulses(with the factor of 3 multiplexing accounted for) are needed forelevation scanning, for each azimuth beam. As a result, the acquisitiontime increases proportionately to approximately 220 ms. If multiplepulses are needed for each vector for multiple depths of focus, theacquisition time further increases proportionately. For platen 468utilizing 1.5D array substrates, on the order of 10 elevation beams(i.e., pulses assuming 1 pulse per beam) are needed to fill the 1 cm gap(each slice is about 1 mm thick in the elevation dimension) betweenadjacent array substrates. Assuming that the adjacent 1.5D arraysubstrates are operated simultaneously (or near simultaneously), then330 pulses are needed for 3D volumetric scanning, requiring anacquisition time of 66 ms. Again, multiple depths of focus will multiplythis acquisition time.

The discussion in the preceding paragraph illustrates the need to reduceacquisition time for full 2D scanning arrays, and for platen 468 of theabove example, utilizing 1.5D array substrates, in certain applications.Conventional azimuth electronic scanning (and by extension, elevationscanning) transmits pulses sequentially; that is, the first pulse istransmitted (i.e. first pressure wave) and received (i.e. secondpressure wave) prior to transmitting the next pulse. In order to reducethe total acquisition time for 3D volumetric data acquisition (whichincludes 2D acquisition as a special case as described earlier), severalpulses are to be transmitted in rapid succession (i.e., one followingimmediately after the preceding pulse is launched) so that severalpulses are in-flight simultaneously. Each of the in-flight pulses istransmitted with a different transmit beam separated significantly(i.e., in azimuth and/or elevation) from the other transmit beamsassociated with the other in-flight pulses. This beam-pulse interleavingtechnique reduces (to acceptable levels) the co-beam-pulse interferencecaused by the other in-flight pulse returns when forming the receivebeams (i.e., vectors) associated with a given in-flight pulse's returns.Furthermore, the beam-pulse interleaving technique causes theacquisition time to be reduced by a factor equal to the average numberof in-flight-pulses. The selection of beam-pulse sets for use with thisbeam-pulse interleaving technique need not be regular, and can beoptimized both in terms of the number of beams per set and theirlocations (in azimuth, elevation or both) so as to meet the acquisitiontime requirements while maintaining specifications on co-beam-pulseinterference rejection. The costs associated with employing thebeam-pulse interleaving technique are an increased minimum depth (range)of operation which corresponds to the total time taken to transmit thein-flight pulses in rapid succession (which is small in practice), andincreased computational requirements to form the multiple receive beams(vectors) in parallel, in order to maintain real-time performance.

A variation to the beam pulse interleaving technique described abovewould cause successive in-flight pulses to be launched each using adifferent waveform code (i.e., waveform pulse interleaving) which variesany or all of the amplitude, frequency or phase of the transmitted pulserather than (or in addition to) directing each pulse to differentspatial directions or beams. In this way, the co-waveform pulseinterference can be reduced to acceptable levels, thereby separating theinterfering returns from different in-flight pulses. Such approaches arelikely to be more suitable for narrow band systems than for wide bandsystems.

An alternative to the rapid, successive transmission of in-flight pulseseach directed using a different transmit beam is to form a compositetransmit beam pattern representing the superposition of the individualbeam patterns associated with the in-flight pulses, and transmitting asingle pulse. This alternative approach, however, can suffer fromreduced power directed to the associated beam directions, and hencereduced power on receive.

It is emphasized here that the aforementioned beam-pulse interleavingtechnique is applicable to both full 2D scanning arrays as well as thosebased on 1.5D technology as described in the instant disclosure. Thescanning functionality provided by the beam-pulse interleaving techniqueforms part of the phased-array signal processing circuitry 470.

Phased-array signal processing circuitry 470, like acquisitioncontroller 442 as a whole and other components shown in FIG. 29, isrealizable in the form of digital processor circuits modified byprogramming to operate transducer packages or apertures 466 as a phasedarray. Thus, phased-array signal processing circuitry 470 and the signalprocessing and control elements of FIG. 29 are all realizable by aproperly programmed digital computer. It should be noted that theterminology “phased array” used throughout this application is intendedto be applicable to both narrow-band and wide-band waveforms, although,strictly speaking, the term originates from systems employingnarrow-band waveforms where the phase of a signal is varied toeffectuate scanning. It is understood that for wide-band waveforms suchas those often employed in ultrasound systems, it is the time delay ofthe signals (rather than the phase) that must be varied across a givendata gathering aperture in order to effectuate electronic scanning. Inthe instant disclosure, the term “delay” is intended to cover both aphase variation and a time delay as applicable in the use of wide-bandwaveforms.

It is of interest that imaging occurs in the far field of eachindividual transducer element 438 and in the near field of package orarray aperture 436. The near-field variation of a wavefront across anaperture 438 is quadratic. As a result, focusing an array aperture in aphased-array process is achieved by computing and applying theappropriate quadratic time delays, for the location in question that isbeing focused. A variety of approaches are known to those skilled in theart to optimize this process for a given application.

Of course, the physics of ultrasound are well documented and understood.Software for any of the ultrasonic imaging systems herein entails astraightforward application of the appropriate wave equations. See, forinstance, Principles of Aperture and Array System Design, B. D.Steinberg, John Wiley, 1976, and Ultrasonic Imaging Using Arrays, Proc.IEEE, Vol. 67, No. 4, April 1979, pp 484-495.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. It is to be understood, for instance, that thevarious processing functions (e.g., aperture formation, coherentaperture combining, self-cohering algorithm calculation, etc.) may beperformed by a specially programmed general purpose computer asdisclosed herein or, alternatively, by hard wired circuits. Hard wiringmay be especially advantageous for various preprocessing and calibrationor position determination computations.

Moreover, it is to be noted that multiple images may be provided on asingle video screen, pursuant to conventional windows-type overlaytechniques. Thus, one window or video image may show an organ from onepoint of view or angle, while another window on the same screen may showthe same organ from a different vantage point. Alternatively, one windowmay show a first organ, while another window displays one or more organsunderlying the first organ. In this case, the underlying organs may beshown in phantom line in the first window, while the overlying organs isshown in phantom lines in the second window. Of course, all suchoperating modes apply to multiple video screens as well as to a singlescreen. Thus, one screen may display an overlying organ from one angle,while an adjacent organ displays an underlying organ from a differentangle. A display window on a video screen of the present invention maybe used alternatively for the display of textual information pertainingto the tissues and organs displayed in other video windows. Suchinformation may include diagnostic information determined by theanalyzing computer.

It is to be further noted that the 1.5D transducer arrays discussedherein could be replaced by so-called 1.75D arrays. Accordingly, theterm “1.5D transducer array” as used herein should be understood toencompass 1.75D transducer arrays, as well.

Accordingly, it is to be understood that the drawings and descriptionsherein are profered by way of example to facilitate comprehension of theinvention and should not be construed to limit the scope thereof.

1. A medical method comprising: providing a carrier holding amultiplicity of electromechanical transducers defining respective datagathering apertures; placing said carrier and a patient adjacent to oneanother so that said transducers are disposed in effectivepressure-wave-transmitting contact with the patient; supplying a firstplurality of said transducers with electrical signals of at least onepre-established ultrasonic frequency to produce first pressure waves inthe patient; receiving, via a second plurality of said transducers,second pressure waves produced at internal tissue structures of thepatient in response to said first pressure waves; and performingelectronic 3D volumetric data acquisition and imaging of said internaltissue structures by analyzing signals generated by said secondplurality of said transducers in response to said second pressure waves,the analyzing of signals generated by said second plurality of saidtransducers including coherently combining structural data from therespective data-gathering apertures, said carrier including a pluralityof rigid substrates containing said data-gathering apertures, thecoherently combining of structural data from the respectivedata-gathering apertures including determining relative positions andorientations of said substrates relative to one another, the determiningof relative positions and orientations of said substrates includingexecuting computations according to a self-cohering algorithm.
 2. Themethod defined in claim 1 wherein each of said substrates is providedwith a plurality of point scatterers, the determining of relativepositions and orientations of said substrates including periodicallyscanning said point scatterers with ultrasonic pressure waves andcalculating instantaneous positions of said point scatterers.
 3. Themethod defined in claim 2 wherein the determining of relative positionsand orientations of said carriers includes executing computationsaccording to a self-cohering algorithm.
 4. The method defined in claim 1wherein the determining of relative positions and orientations of saidcarriers includes periodically energizing at some of said transducerswith at least one predetermined electrical frequency and calculatinginstantaneous positions of the transducers so energized.
 5. A medicalscanning method comprising: providing a plurality of electromechanicalsensors disposed in data-gathering arrays or apertures on respectiverigid substrates mounted to a flexible carrier; disposing said carrierin relation to a patient; after the disposing of said carrier,activating said sensors to effectuate a solely electronicultrasonic-wave scan of internal organic structures of the patientresulting in encoded three-dimensional structural data pertaining to theinternal organic structures, the activating of said sensors includingexciting said sensors to define said data-gathering arrays or apertures;the activating of said sensors including generating a plurality oftissue-scanning beams via respective ones of said data-gathering arraysor apertures to capture or produce structural data pertaining to saidinternal organic structures and combining the structural data from saiddata-gathering arrays or apertures; and operating on the data from saidsensors to produce an electronically encoded three-dimensional model oranalog of said internal organic structures.
 6. The method defined inclaim 5 wherein said three dimensional model is produced from said dataalone.
 7. The method defined in claim 6, further comprising generatingan image of at least one of said internal structures from said model.